all: Update Go Module to Go 1.20 (#1246)

Reference: https://pkg.go.dev/math/rand#Seed
Reference: #1245

Previously from `golangci-lint` after Go 1.20 upgrade:

```
helper/acctest/random.go:24:2: SA1019: rand.Seed has been deprecated since Go 1.20 and an alternative has been available since Go 1.0: As of Go 1.20 there is no reason to call Seed with a random value. Programs that call Seed with a known value to get a specific sequence of results should use New(NewSource(seed)) to obtain a local random generator. (staticcheck)
	rand.Seed(time.Now().UTC().UnixNano())
	^
```

.changes/unreleased/NOTES-20230906-055849.yaml

@@ -0,0 +1,8 @@
+kind: NOTES
+body: 'all: This Go module has been updated to Go 1.20 per the [Go support
+  policy](https://go.dev/doc/devel/release#policy). It is recommended to review
+  the [Go 1.20 release notes](https://go.dev/doc/go1.20) before upgrading. Any
+  consumers building on earlier Go versions may experience errors.'
+time: 2023-09-06T05:58:49.879435-04:00
+custom:
+  Issue: "1245"

.github/workflows/ci-go.yml

@@ -48,7 +48,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go-version: [ '1.20', '1.19' ]
+        go-version: [ '1.21', '1.20' ]
     steps:
       - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # v3.5.3
       - uses: actions/setup-go@93397bea11091df50f3d7e59dc26a7711a8bcfbe # v4.1.0

README.md

@@ -18,7 +18,7 @@ When running provider tests, Terraform 0.12.26 or later is needed for version 2.
 
 This project follows the [support policy](https://golang.org/doc/devel/release.html#policy) of Go as its support policy. The two latest major releases of Go are supported by the project.
 
-Currently, that means Go **1.19** or later must be used when including this project as a dependency.
+Currently, that means Go **1.20** or later must be used when including this project as a dependency.
 
 ## Getting Started
 

go.mod

@@ -1,6 +1,6 @@
 module github.com/hashicorp/terraform-plugin-sdk/v2
 
-go 1.19
+go 1.20
 
 require (
 	github.com/google/go-cmp v0.5.9

helper/acctest/random.go

@@ -20,10 +20,6 @@ import (
 	"golang.org/x/crypto/ssh"
 )
 
-func init() {
-	rand.Seed(time.Now().UTC().UnixNano())
-}
-
 // Helpers for generating random tidbits for use in identifiers to prevent
 // collisions in acceptance tests.
 

tools/go.mod

@@ -1,6 +1,6 @@
 module tools
 
-go 1.19
+go 1.20
 
 require github.com/hashicorp/copywrite v0.16.4
 

website/docs/plugin/sdkv2/testing/acceptance-tests/index.mdx

@@ -142,7 +142,7 @@ Create a [GitHub Actions workflow](https://docs.github.com/en/actions/using-work
 
 Use the [`matrix`](https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#jobsjob_idstrategymatrix) strategy for more advanced configuration, such as running acceptance testing against multiple Terraform CLI versions.
 
-The following example workflow runs acceptance testing for the provider using the latest patch versions of Go 1.19 and Terraform CLI 1.3:
+The following example workflow runs acceptance testing for the provider using the latest patch versions of Go defined in the `go.mod` file and Terraform CLI 1.5:
 
 ```yaml
 name: Terraform Provider Tests
@@ -163,12 +163,12 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
-      - uses: actions/setup-go@v3
+      - uses: actions/setup-go@v4
         with:
-          go-version: '1.19'
+          go-version-file: 'go.mod'
       - uses: hashicorp/setup-terraform@v2
         with:
-          terraform_version: '1.3.*'
+          terraform_version: '1.5.*'
           terraform_wrapper: false
       - run: go test -v -cover ./...
         env:
@@ -178,14 +178,14 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
-      - uses: actions/setup-go@v3
+      - uses: actions/setup-go@v4
         with:
-          go-version: '1.19'
+          go-version-file: 'go.mod'
       - run: go test -v -cover ./...
 ```
 
 
-The following example workflow runs acceptance testing for the provider using the latest patch versions of Go 1.19 and Terraform CLI 0.12 through 1.3:
+The following example workflow runs acceptance testing for the provider using the latest patch versions of Go defined in the `go.mod` file and Terraform CLI 0.12 through 1.5:
 
 ```yaml
 name: Terraform Provider Tests
@@ -216,11 +216,13 @@ jobs:
           - '1.1.*'
           - '1.2.*'
           - '1.3.*'
+          - '1.4.*'
+          - '1.5.*'
     steps:
       - uses: actions/checkout@v3
-      - uses: actions/setup-go@v3
+      - uses: actions/setup-go@v4
         with:
-          go-version: '1.19'
+          go-version-file: 'go.mod'
       - uses: hashicorp/setup-terraform@v2
         with:
           terraform_version: ${{ matrix.terraform-version }}
@@ -233,9 +235,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
-      - uses: actions/setup-go@v3
+      - uses: actions/setup-go@v4
         with:
-          go-version: '1.19'
+          go-version-file: 'go.mod'
       - run: go test -v -cover ./...
 ```