build: configure dependabot

Group updates into non-breaking security, non-breaking version, and breaking,
on a weekly batch cycle @ 6AM UTC Monday morning. Also set prefix to conform with
Conventional Commits, Angular types.

Author: rhyslbw

.github/dependabot.yml

@@ -0,0 +1,26 @@
+# https://docs.github.com/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file
+
+version: 2
+updates:
+  - package-ecosystem: npm
+    directory: "/"
+    schedule:
+      interval: weekly
+      day: monday
+      time: "06:00"
+    commit-message:
+      prefix: build
+    groups:
+      security-updates:
+        applies-to: security-updates
+        update-types:
+          - "patch"
+          - "minor"
+      non-breaking-version-updates:
+        applies-to: version-updates
+        update-types:
+          - "patch"
+          - "minor"
+      breaking-updates:
+        update-types:
+          - "major"