ci,test: Add strategy.matrix.toolchain

Run test job on rust stable and 1.85.0 (MSRV).

test and lint jobs now use
`actions-rust-lang/setup-rust-toolchain`.

Author: ValuedMammal

.github/workflows/rust.yml

@@ -9,9 +9,21 @@ env:
 
 jobs:
   test:
+    name: Test
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        toolchain:
+          - 1.85.0 # MSRV
+          - stable
     steps:
-    - uses: actions/checkout@v6
+    - name: Checkout
+      uses: actions/checkout@v6
+    - name: Install Rust
+      uses: actions-rust-lang/setup-rust-toolchain@v1
+      with:
+        toolchain: ${{ matrix.toolchain }}
+        cache: true
     - name: Check features
       run: |
         cargo check --no-default-features
@@ -22,9 +34,16 @@ jobs:
       run: cargo test --no-fail-fast
 
   lint:
+    name: Lint
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v6
+    - name: Checkout
+      uses: actions/checkout@v6
+    - name: Install Rust
+      uses: actions-rust-lang/setup-rust-toolchain@v1
+      with:
+        toolchain: stable
+        cache: true
     - name: Rustfmt
       run: cargo fmt --all --check
     - name: Lint