Pin checkout action to v5 to drop the Node 20 deprecation

Author: craigthackerx

.github/workflows/ci.yml

@@ -15,7 +15,7 @@ jobs:
     name: Shell scripts
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - name: Install shellcheck
         run: |
@@ -59,7 +59,7 @@ jobs:
     name: No committed secrets
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       # Belt and braces alongside .gitignore. Catches a file that was force
       # added past the ignore rules.