nedgradere checkout action till v1

Ikke støtte før short sha ref i v2 per actions/checkout#265

Author: albrektsson

.github/workflows/promote-command.yml

@@ -32,7 +32,7 @@ jobs:
           echo "TAG=$(echo ${{ steps.issue_comment.outputs.title }} | awk -F- '{print $NF}')" >> $GITHUB_ENV
 
       - name: Sjekk ut kode
-        uses: actions/checkout@v2
+        uses: actions/checkout@v1
         with:
           ref: ${{ env.TAG }}