chore: bump MSRV to 1.73 as required by dependencies

.github/workflows/ci.yml

@@ -22,7 +22,7 @@ jobs:
           - conf: nightly
             toolchain: nightly
           - conf: msrv
-            toolchain: '1.66'
+            toolchain: '1.73.0'
     env:
       RUST_BACKTRACE: 1
 

Cargo.toml

@@ -21,7 +21,7 @@ exclude = [
   "test/*",
 ]
 edition = "2021"
-rust-version = "1.66"
+rust-version = "1.73.0"
 
 [dependencies]
 crc32fast = { version = "1.4.0", default-features = false, optional = true }

README.md

@@ -10,7 +10,7 @@ This is a reimplementation of the [Zopfli](https://github.com/google/zopfli) com
 
 Carol Nichols started the Rust implementation as an experiment in incrementally rewriting a C library in Rust, keeping the project compiling at every step. For more information about that experiment, see [the slides for a talk she gave about it](https://github.com/carols10cents/rust-out-your-c-talk) and [the repo as it was for the experiment](https://github.com/carols10cents/zopfli).
 
-The minimum supported Rust version (MSRV) for this crate is 1.66. Bumping this version is not considered a breaking change for semantic versioning purposes. We will try to do it only when we estimate that such a bump would not cause widespread inconvenience or breakage.
+The minimum supported Rust version (MSRV) for this crate is 1.73. Bumping this version is not considered a breaking change for semantic versioning purposes. We will try to do it only when we estimate that such a bump would not cause widespread inconvenience or breakage.
 
 ## How to build