ci: remove ok-to-test label after commenting

Once the comments have been added, the `ok-to-test` label can be
removed. This makes it possible to simplify the Mergify configuration.

Signed-off-by: Niels de Vos <ndevos@redhat.com>

.github/workflows/pull-request-commentor.yaml

@@ -113,3 +113,13 @@ jobs:
           issue-number: ${{ github.event.pull_request.number }}
           body: |
             /test ci/centos/upgrade-tests-rbd
+
+      - name: remove ok-to-test-label after commenting
+        # yamllint disable rule:line-length
+        run: |
+            curl --silent --fail-with-body \
+              -X DELETE \
+              -H 'Accept: application/vnd.github.v3+json' \
+              -H 'Authorization: token ${{ github.token }}' \
+              'https://api.github.com/repos/${{ github.repository }}/issues/${{ github.event.number }}/labels/ok-to-test'
+        # yamllint enable rule:line-length