Update actions/checkout@v4 -> v5

Fix update-revs.sh to recognize only the intended `required: true`

.github/workflows/ci.yml

@@ -24,7 +24,7 @@ jobs:
             rust: 1.0.0
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: ./
         name: Run dtolnay/rust-toolchain${{contains(matrix.rust, ' ') && ' for ' || '@'}}${{matrix.rust}}
         id: toolchain

README.md

@@ -16,7 +16,7 @@ jobs:
     name: cargo test
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: dtolnay/rust-toolchain@stable
       - run: cargo test --all-features
 ```

action.yml

@@ -34,7 +34,7 @@ runs:
       run: |
         : parse toolchain version
         if [[ -z $toolchain ]]; then
-          : GitHub does not enforce 'required: true' inputs itself. https://github.com/actions/runner/issues/1070
+          # GitHub does not enforce `required: true` inputs itself. https://github.com/actions/runner/issues/1070
           echo "'toolchain' is a required input" >&2
           exit 1
         elif [[ $toolchain =~ ^stable' '[0-9]+' '(year|month|week|day)s?' 'ago$ ]]; then

scripts/update-revs.sh

@@ -33,7 +33,7 @@ for rev in `releases` stable beta nightly; do
     if [[ $rev == 1* ]]; then
         sed -i "/^  toolchain:/,+2d; s/\${{inputs\.toolchain}}/$rev/" action.yml
     else
-        sed -i "s/required: true/required: false\n    default: $rev/" action.yml
+        sed -i "s/^    required: true$/    required: false\n    default: $rev/" action.yml
     fi
     git add action.yml
     git commit --quiet --message "toolchain: $rev"