Added dependabot for GitHub Actions

How about using dependabot in this way? When this works, a PullRequest is created as follows: - ruby/bigdecimal#242 It was created with reference to the following: - ruby/csv#265
MarttiCheng · Nov 30, 2022 · 30adda2 · 30adda2
1 parent 90a1f2a
commit 30adda2
Showing 1 changed file with 6 additions and 0 deletions.
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'