cd: clarify conditions

Trigger only on "push to master" and "tag push" instead of "any action
with master" branch and "any action with tag". For now, it doesn't
change anything since the workflow is triggered only on push, but it is
possible that it would be extended in the future.

Author: DifferentialOrange

.github/workflows/push_rockspec.yaml

@@ -23,7 +23,7 @@ jobs:
 
   push-scm-rockspec:
     runs-on: ubuntu-20.04
-    if: github.ref == 'refs/heads/master'
+    if: ${{ github.event_name == 'push' && github.ref == 'refs/heads/master' }}
     steps:
       - uses: actions/checkout@master
 
@@ -34,7 +34,7 @@ jobs:
 
   push-tagged-rockspec:
     runs-on: ubuntu-20.04
-    if: startsWith(github.ref, 'refs/tags')
+    if: ${{ github.event_name == 'push' && startsWith(github.ref, 'refs/tags/') }}
     needs: version-check
     steps:
       - uses: actions/checkout@master