Update actions/checkout to v6 in linter workflow

Author: pablomendezroyo

.github/workflows/linter.yml

@@ -21,7 +21,7 @@ jobs:
 
     steps:
       - name: Checkout Code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           # Full git history is needed to get a proper list of changed files within `super-linter`
           fetch-depth: 0
@@ -44,7 +44,7 @@ jobs:
 
     steps:
       - name: Checkout Code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Install zsh (Ubuntu)
         if: runner.os == 'Linux'