ci: pin pypa/gh-action-pypi-publish to full commit SHA (#82)

Org policy requires all actions pinned to full-length SHAs.
Missed during the original SHA-pinning pass in 09dc062.

Author: 27Bslash6

.github/workflows/release-please.yml

@@ -152,4 +152,4 @@ jobs:
           path: dist
 
       - name: Publish to PyPI (Trusted Publishing)
-        uses: pypa/gh-action-pypi-publish@release/v1
+        uses: pypa/gh-action-pypi-publish@ed0c53931b1dc9bd32cbe73a98c7f6766f8a527e # release/v1