bump *tested* MSRV to 1.63

That way it should compile with minimal versions.

Reason for this is the following:

````
error: package `cc v1.0.98` cannot be built because it requires rustc 1.63 or newer, while the currently active rustc version is 1.56.1
````

Note that the expressed MSRV is still a lower one as it may work for
some people that use different settings and/or configuration.

.github/workflows/main.yml

@@ -83,7 +83,7 @@ jobs:
         os: [windows-2022, macos-latest, ubuntu-latest]
     env:
       # If this is changed to pass tests, then set `rust-version` in `Cargo.toml` to the same version.
-      version: 1.56.1
+      version: 1.63.0
     steps:
       - uses: actions/checkout@v4
       - name: Install Rust (rustup)