Enable Dependabot version updates for Actions

EliahKagan · EliahKagan · commit 8ac188497e7a · 2023-09-10T18:14:06.000-04:00
This enables Dependabot version updates for GitHub Actions only
(not Python dependencies), using the exact same configuration as in
GitPython.
diff --git a/.github/dependabot.yml b/.github/dependabot.yml
@@ -0,0 +1,6 @@
+version: 2
+updates:
+- package-ecosystem: "github-actions"
+  directory: "/"
+  schedule:
+      interval: "weekly"
