chore: pin actions/checkout to a full-length commit SHA

Author: tkskto

.github/workflows/lint.yml

@@ -11,7 +11,7 @@ jobs:
     name: Lint (node.js 20 on ubuntu-latest)
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4.1.7
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
       - name: Use node.js 20
         uses: actions/setup-node@v4.0.2
         with:

.github/workflows/test.yml

@@ -11,7 +11,7 @@ jobs:
     name: Test (node.js 20 on ubuntu-latest)
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4.1.7
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
       - name: Use node.js 20
         uses: actions/setup-node@v4.0.2
         with: