.github: temporarily switch to manual updates

Temporarily switch to manual dependencies update workflow to test if it
is updated correctly across the different release branch.

Signed-off-by: Damien Grisonnet <dgrisonn@redhat.com>

.github/workflows/versions.yaml

 name: Upgrade to latest versions
 
-on:
-  schedule:
-    - cron: '37 13 * * 1'
+on: workflow_dispatch
 jobs:
   versions:
     runs-on: ubuntu-latest