build: use real credentials

Author: sgratzl

.github/workflows/ci_fast.yaml

@@ -40,8 +40,8 @@ jobs:
         uses: docker/login-action@v1
         with:
           registry: ghcr.io
-          username: ${{ secrets.CR_USER }}
-          password: ${{ secrets.CR_PAT }}
+          username: cmu-delphi-deploy-machine
+          password: ${{ secrets.CMU_DELPHI_DEPLOY_MACHINE_PAT }}
 
       - name: Build, tag, and push image to Github
         env: