CI: pin actions by SHA

This eliminates the possibility of a tag being changed under
us.

Author: tacaswell

.github/.githubold/workflows/main.yml

@@ -5,7 +5,7 @@ jobs:
     name: Run CircleCI artifacts redirector
     steps:
       - name: GitHub Action step
-        uses: larsoner/circleci-artifacts-redirector-action@master
+        uses: scientific-python/circleci-artifacts-redirector-action@7eafdb60666f57706a5525a2f5eb76224dc8779b  # v1.1.0
         with:
           repo-token: ${{ secrets.GITHUB_TOKEN }}
           artifact-path: 0/docs/_build/html/index.html