Pin publish step to pypi environment, and drop obsolete templates

Author: fizyk

.github/ISSUE_TEMPLATE.rst

@@ -13,6 +13,7 @@ jobs:
     name: Publish Python 🐍 distributions 📦 to PyPI
     needs: build
     runs-on: ubuntu-latest
+    environment: pypi
     permissions:
       id-token: write
     steps: