keepalive: force commit when triggered manually

When issuing a workflow dispatch, the intention is to keep the
repository alive, i.e. a commit _must_ be made, one way or another.
Let's side-step the 3-weeks logic in that scenario.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

.github/workflows/keepalive.yml

@@ -33,7 +33,8 @@ jobs:
         id: commit
         if: steps.merge.outputs.result != 'merged'
         run: |
-          if test 0 -lt $(git rev-list --count --since=3.weeks.ago HEAD)
+          if test workflow_dispatch != '${{ github.event_name }}' &&
+            test 0 -lt $(git rev-list --count --since=3.weeks.ago HEAD)
           then
             echo "::notice::No need to keep alive, there were commits in the last three weeks"
             echo "result=skip-push" >>$GITHUB_OUTPUT