msrv: Simplify installation of Rust toolchain

Author: uklotzde

.github/workflows/msrv.yaml

@@ -24,11 +24,8 @@ jobs:
           sudo apt-get update && sudo apt-get install -y libasound2-dev libjack-jackd2-dev cmake
 
       - name: Install Rust toolchain
-        uses: dtolnay/rust-toolchain@master
-        with:
-          # Aligned with `rust-version` in `Cargo.toml`
-          # The quoting is required, otherwise versions that end with 0 would be interpreted as a number
-          toolchain: "1.70"
+        # Aligned with `rust-version` in `Cargo.toml`
+        uses: dtolnay/[email protected]
 
       - name: Check out repository
         uses: actions/checkout@v3