ci: Use admin token to trigger CI workflows on ff (#1119)

A known *feature* of github actions does not allow CI to run after a fast
forward has been issued on a release branch. This might be a curse to
keep a linear history AND have images built on docker hub. By using an
`ADMIN_TOKEN` secret the action would run as an admin performed an
operation, making CI run after a fast forward.

Signed-off-by: Luca Zaninotto <luca.zaninotto@secomind.com>

Author: lusergit

.github/workflows/fast-forward.yaml

@@ -38,5 +38,6 @@ jobs:
       - name: Fast forwarding
         uses: sequoia-pgp/fast-forward@v1
         with:
+          github_token: ${{ secrets.ADMIN_TOKEN }}
           merge: true
           comment: on-error