Bumps to actions/checkout@v4 (#1196)

.github/workflows/build-distros.yml

@@ -37,7 +37,7 @@ jobs:
 
     steps:
     - name: Check out alire-index
-      uses: actions/checkout@v2
+      uses: actions/checkout@v4
       with:
         fetch-depth: 0
         # Needed to be able to diff and obtain changed files. Furthermore, we
@@ -46,7 +46,7 @@ jobs:
         # check-author action).
 
     - name: Check out alire-index-checks
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
       with:
         repository: ${{env.CHECKS_ORG}}/${{env.CHECKS_REPO}}
         ref: ${{github.base_ref}}