Add permissions for generate-templates Action to create PR

[JoeyBarnes]

Add permissions for generate-templates Action to create PR

Replace this with a brief description of what this Pull Request fixes, changes, etc.

This PR fixes/adds/changes/removes

1. Add permissions for generate-templates Action to create PR

Breaking Changes

As part of this Pull Request I have

• Read the Contribution Guide and ensured this PR is compliant with the guide
• Checked for duplicate Pull Requests
• Associated it with relevant GitHub Issues or ADO Work Items (Internal Only)
• Ensured my code/branch is up-to-date with the latest changes in the main branch
• Ensured PR tests are passing
• Updated relevant and associated documentation (e.g. Contribution Guide, Docs etc.)

[arjenhuitema]

LGTM