Enable dependabot updates for github actions

Author: ndevenish

.github/dependabot.yml

@@ -5,3 +5,7 @@ updates:
     open-pull-requests-limit: 0
     schedule:
       interval: "quarterly"
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: quarterly

.github/workflows/build_and_test.yml

@@ -75,4 +75,4 @@ jobs:
           name: artifact
           path: dist
       - name: Publish package distributions to PyPI
-        uses: pypa/gh-action-pypi-publish@76f52bc884231f62b9a034ebfe128415bbaabdfc
+        uses: pypa/gh-action-pypi-publish@76f52bc884231f62b9a034ebfe128415bbaabdfc # v1.12.4