Upload to pypi whenever a branch starting with "release/" is released (invoke-ai#4875)

## What type of PR is this? (check all applicable)


- [X] Optimization
- 

## Have you discussed this change with the InvokeAI team?
- [X] Yes
- [ ] No, because:

      
## Have you updated all relevant documentation?
- [X] Yes
- [ ] No


## Description

This PR changes the pypi-release workflow so that it will upload to PyPi
whenever a release is initiated from the `main` branch or another branch
beginning with `release/`. Previous support for v2.3 branches has been
removed.

Author: lstein

.github/workflows/pypi-release.yml

@@ -28,7 +28,7 @@ jobs:
         run: twine check dist/*
 
       - name: check PyPI versions
-        if: github.ref == 'refs/heads/main' || github.ref == 'refs/heads/v2.3' || github.ref == 'refs/heads/v3.3.0post1'
+        if: github.ref == 'refs/heads/main' || startsWith(github.ref, 'refs/heads/release/')
         run: |
           pip install --upgrade requests
           python -c "\