Bump actions/checkout from 3 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

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

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
     name: Run Linters
     runs-on: ubuntu-20.04
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Ensure +x on CI directory
         run: |
           chmod -R +x ./tools/ci
@@ -38,7 +38,7 @@ jobs:
     name: DreamChecker
     runs-on: ubuntu-20.04
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Cache SpacemanDMM
         uses: actions/cache@v3
@@ -71,7 +71,7 @@ jobs:
     # needs: ['file_tests', 'dreamchecker']
     runs-on: ubuntu-20.04
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Ensure +x on CI directory
         run: |
           chmod -R +x ./tools/ci

.github/workflows/render_nanomaps.yml

@@ -22,7 +22,7 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
     - name: Clone
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Branch
       run: |