ci: Pin pypa actions

Author: jpmckinney

.github/workflows/pypi.yml

@@ -24,7 +24,7 @@ jobs:
         with:
           name: python-package-distributions
           path: dist/
-      - uses: pypa/gh-action-pypi-publish@release/v1
+      - uses: pypa/gh-action-pypi-publish@76f52bc884231f62b9a034ebfe128415bbaabdfc # v1.12.4
         with:
           repository-url: https://test.pypi.org/legacy/
           skip-existing: true
@@ -39,4 +39,4 @@ jobs:
         with:
           name: python-package-distributions
           path: dist/
-      - uses: pypa/gh-action-pypi-publish@release/v1
+      - uses: pypa/gh-action-pypi-publish@76f52bc884231f62b9a034ebfe128415bbaabdfc # v1.12.4