Update Rust CI to maintain name for cargo (MSRV) job

Signed-off-by: Andrej Orsula <[email protected]>

.github/workflows/rust.yml

@@ -14,6 +14,7 @@ concurrency:
   cancel-in-progress: true
 
 env:
+  MSRV: "1.74"
   PYTHON_VERSION: "3.10"
   CARGO_TERM_COLOR: always
   LIB_PACKAGE_NAME: pyo3_bindgen
@@ -41,7 +42,7 @@ jobs:
       fail-fast: false
       matrix:
         toolchain:
-          - "1.74" # Minimal supported Rust version (MSRV)
+          - MSRV
           - stable
           - beta
     steps:
@@ -50,9 +51,19 @@ jobs:
         with:
           save-if: ${{ github.event_name == 'push'}}
       - uses: dtolnay/rust-toolchain@master
+        if: ${{ matrix.toolchain != 'MSRV' && matrix.toolchain != 'stable' }}
+        with:
+          toolchain: ${{ matrix.toolchain }}
+      - uses: dtolnay/rust-toolchain@master
+        if: ${{ matrix.toolchain == 'MSRV' }}
+        with:
+          toolchain: ${{ env.MSRV }}
+      - uses: dtolnay/rust-toolchain@master
+        if: ${{ matrix.toolchain == 'stable' }}
         with:
           toolchain: ${{ matrix.toolchain }}
           components: clippy
+
       - uses: actions/setup-python@v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}