Add dependabot.yml

Author: jerone

.github/dependabot.yml

@@ -2,8 +2,14 @@
 # https://docs.github.com/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file
 
 version: 2
+
 updates:
   - package-ecosystem: "nuget"
-    directory: "/" # Location of package manifests
+    directory: "/"
     schedule:
       interval: "weekly"
+
+groups:
+  csharpier:
+    patterns:
+    - "csharpier*"