Update actions/checkout action to v4

Author: renovate[bot]

.github/workflows/ci.yaml

@@ -32,7 +32,7 @@ jobs:
     # Steps represent a sequence of tasks that will be executed as part of the job
     steps:
       # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - uses: bazelbuild/setup-bazelisk@v1
       - name: Mount bazel action cache
         uses: actions/cache@v2

.github/workflows/release.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
       - uses: bazelbuild/setup-bazelisk@v1
       - name: Check git state is clean
         run: git status --porcelain