ci: use Cysharp/Actions checkout instead of 3rd party directly

Author: guitarrapc

.github/workflows/build-debug.yml

@@ -30,7 +30,7 @@ jobs:
           UNITY_PASSWORD: "op://${{ vars.OP_VAULT_ACTIONS_PUBLIC }}/UNITY_LICENSE/credential"
           UNITY_SERIAL: "op://${{ vars.OP_VAULT_ACTIONS_PUBLIC }}/UNITY_LICENSE/serial"
 
-      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - uses: Cysharp/Actions/.github/actions/checkout@main
 
       # Execute scripts: Export Package
       # /opt/Unity/Editor/Unity -quit -batchmode -nographics -silent-crashes -logFile -projectPath . -executeMethod PackageExporter.Export

.github/workflows/build-release.yml

@@ -40,7 +40,7 @@ jobs:
           UNITY_PASSWORD: "op://${{ vars.OP_VAULT_ACTIONS_PUBLIC }}/UNITY_LICENSE/credential"
           UNITY_SERIAL: "op://${{ vars.OP_VAULT_ACTIONS_PUBLIC }}/UNITY_LICENSE/serial"
 
-      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - uses: Cysharp/Actions/.github/actions/checkout@main
         with:
           ref: ${{ needs.update-packagejson.outputs.sha }}
       # Execute scripts: Export Package