ci: Move PYTHONWARNINGS filter on build to weekly cron job (#2337)

* Move PYTHONWARNINGS filter to run on a weekly cron job to avoid interrupting
  normal development with errors due to warnings outside of direct user control.

.github/workflows/publish-package.yml

@@ -11,6 +11,9 @@ on:
     - release/v*
   release:
     types: [published]
+  # Run weekly at 1:23 UTC
+  schedule:
+  - cron:  '23 1 * * 0'
   workflow_dispatch:
     inputs:
       publish:
@@ -44,7 +47,13 @@ jobs:
         python -m pip install build twine
         python -m pip list
 
-    - name: Build a wheel and a sdist
+    - name: Build a sdist and wheel
+      if: github.event_name != 'schedule'
+      run: |
+        python -m build .
+
+    - name: Build a sdist and wheel and check for warnings
+      if: github.event_name == 'schedule'
       run: |
         PYTHONWARNINGS=error,default::DeprecationWarning python -m build .