CI: adjust matrix test to install rustfmt during autofmt tests

.github/workflows/main.yml

@@ -124,8 +124,6 @@ jobs:
             }
 
     steps:
-      - uses: actions/checkout@v4
-
       - name: install stable
         uses: dtolnay/rust-toolchain@master
         with:
@@ -141,6 +139,11 @@ jobs:
           workspaces: core -> ../target
           save-if: ${{ matrix.features.key == 'all' }}
 
+      - name: Install rustfmt
+        run: rustup component add rustfmt
+
+      - uses: actions/checkout@v4
+
       - name: test
         run: |
           ${{ env.RUST_CARGO_COMMAND }} ${{ matrix.platform.command }} ${{ matrix.platform.args }} --target ${{ matrix.platform.target }}