Create dependabot.yml

CI logs are showing deprecation warnings coming from action versions, so this adds some automation to ensuring we're always using up to date action versions.

Author: MichaelHatherly

.github/dependabot.yml

@@ -0,0 +1,7 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"
+    open-pull-requests-limit: 1