Update actions/checkout action to v4

Author: renovate[bot]

.github/workflows/changeset.yml

@@ -28,7 +28,7 @@ jobs:
       DEBUG: true
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4
         with:
           fetch-depth: 0
           persist-credentials: false

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
     timeout-minutes: 3
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4
       - name: Install
         run: yarn
       - name: Lint

.github/workflows/release.yml

@@ -11,7 +11,7 @@ jobs:
     timeout-minutes: 10
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4
         with:
           # This makes Actions fetch all Git history so that Changesets can
           # generate changelogs with the correct commits.