Update tag pattern in prep-release pipeline to match dev versions (#674)

The pipeline was not triggered by my `0.8.dev0` tag, which is the
[recommended
format](https://packaging.python.org/en/latest/specifications/version-specifiers/#developmental-releases)
for development releases.

.github/workflows/prep-release.yaml

@@ -2,7 +2,7 @@ name: Build Python 🐍 distributions 📦 and publish to TestPyPI
 on:
   push:
     tags:
-      - '[0-9]+.[0-9]+.[0-9]+*'
+      - '[0-9]+.[0-9]+.*[0-9]+*'
 jobs:
   build-n-publish:
     name: Build Python 🐍 distributions 📦 and publish to TestPyPI