Stick with go <1.19

Go 1.19 has different rules in `gofmt` and may lead to
broken CI builds.

Signed-off-by: Andrea Panattoni <apanatto@redhat.com>

.github/workflows/go.yml

@@ -12,7 +12,7 @@ jobs:
     - name: Set up Go 1.18
       uses: actions/setup-go@v3
       with:
-        go-version: '>=1.18.2'
+        go-version: 1.18.2
 
     - name: Check out code into the Go module directory
       uses: actions/checkout@v2