Add dummy github service

.github/workflows/automerge.yml

@@ -33,9 +33,11 @@ jobs:
             credentials:
                 username: ${{ github.actor }}
                 password: ${{ secrets.github-token }}
+            env:
+                CUMULUSCI_SERVICE_github: '{ "username": "${{ github.actor }}", "token": "NOTUSED", "email": "NOTUSED" }'
         steps:
             - name: Checkout code
-              uses: actions/checkout@v3
+              uses: actions/checkout@v4.2.0
               with:
                   ref: ${{ inputs.branch_name }}