Use Checkout v6

Author: natanfelles

.github/workflows/tests.yml

@@ -15,7 +15,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Install postfix
         run: sudo apt-get install -y postfix
@@ -69,7 +69,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Install postfix
         run: sudo apt-get install -y postfix