Bump actions/checkout from 3 to 4 (#68)

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] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
       matrix: ${{ steps.set-matrix.outputs.matrix }}                                                                    
     steps:                                                                                                              
       - name: Checkout base repo                                                                                        
-        uses: actions/checkout@v3                                                                                       
+        uses: actions/checkout@v4                                                                                       
       - name: Extract the tested GHC versions                                                                           
         id: set-matrix                                                                                                  
         run: |                                                                                                          
@@ -44,7 +44,7 @@ jobs:
         ports:
           - 5432:5432
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
       if: github.event.action == 'opened' || github.event.action == 'synchronize' || github.event.ref == 'refs/heads/main'
 
     - name: "Configure ghcup"

.github/workflows/linting.yml

@@ -9,7 +9,7 @@ jobs:
   fourmolu:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - uses: fourmolu/fourmolu-action@v8
       with:
@@ -20,7 +20,7 @@ jobs:
   hlint:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: 'Set up HLint'
       uses: rwe/actions-hlint-setup@v1