Bump actions/checkout from 4.1.7 to 4.2.0 (grpc#741)

Author: dependabot[bot]

.github/workflows/dart.yml

@@ -18,7 +18,7 @@ jobs:
       matrix:
         sdk: [3.5, dev]
     steps:
-      - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
+      - uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
       - uses: dart-lang/setup-dart@0a8a0fc875eb934c15d08629302413c671d3f672
         with:
           sdk: ${{ matrix.sdk }}
@@ -70,7 +70,7 @@ jobs:
           - os: macos-latest
             platform: chrome
     steps:
-      - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
+      - uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
       - uses: dart-lang/setup-dart@0a8a0fc875eb934c15d08629302413c671d3f672
         with:
           sdk: ${{ matrix.sdk }}