Upgrade to GitHub-native Dependabot (#80)

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

.github/dependabot.yml

@@ -1,17 +1,7 @@
 version: 2
 updates:
-  - package-ecosystem: "github-actions"
-    # default location of `.github/workflows`
-    directory: "/"
-    open-pull-requests-limit: 10
-    schedule:
-      interval: "weekly"
-
-  - package-ecosystem: "nuget"
-    # location of package manifests
-    directory: "/"
-    open-pull-requests-limit: 10
-    schedule:
-      interval: "daily"
-
-# Built with ❤ by [Pipeline Foundation](https://pipeline.foundation)
+- package-ecosystem: nuget
+  directory: "/"
+  schedule:
+    interval: daily
+  open-pull-requests-limit: 10