add grouped dependency updates (#59)

### What kind of change does this PR introduce?

* Adds grouped updates to the dependabot configuration

### Does this PR introduce a breaking change?

No.

{{cookiecutter.project_slug}}/.github/dependabot.yml

@@ -1,13 +1,22 @@
+# Please see the documentation for all configuration options:
+# https://docs.github.com/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file
+
 version: 2
 updates:
   - package-ecosystem: github-actions
-    directory: /.github/workflows/
+    directory: /.github/workflows
     schedule:
       interval: monthly
-    open-pull-requests-limit: 10
+    groups:
+      actions:
+        patterns:
+          - "*"
 
   - package-ecosystem: pip
     directory: /
     schedule:
       interval: monthly
-    open-pull-requests-limit: 10
+    groups:
+      python:
+        patterns:
+          - "*"