Bump actions/checkout from 1 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 1 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v1...v4)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/CI.yml

@@ -32,7 +32,7 @@ jobs:
 
     steps:
       - name: Check out code
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0 # need to checkout "all commits" for certain features to work (e.g., get all changed files)
 
@@ -103,7 +103,7 @@ jobs:
         with:
           go-version: ^1.13
       - name: Checkout Code
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
 
       - name: Load CI Environment from .ci_env
         id: load_ci_env
@@ -130,7 +130,7 @@ jobs:
       GIT_SHA: ${{ needs.prepare_ci_run.outputs.GIT_SHA }}
     steps:
       - name: Checkout Code
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
 
       - name: Load CI Environment from .ci_env
         id: load_ci_env

.github/workflows/reviewdog.yml

@@ -11,7 +11,7 @@ jobs:
           go-version: 1.13
         id: go
       - name: Check out code.
-        uses: actions/checkout@v1
+        uses: actions/checkout@v4
       - name: Install linters
         run: '( mkdir linters && cd linters && go get golang.org/x/lint/golint )'
       - uses: reviewdog/action-setup@v1