chore(ci): add Dependabot with monthly grouped updates

Signed-off-by: Yordis Prieto <yordis.prieto@gmail.com>

Author: yordis

.github/dependabot.yml

@@ -0,0 +1,19 @@
+version: 2
+updates:
+  - package-ecosystem: cargo
+    directory: /rsworkspace
+    schedule:
+      interval: monthly
+    groups:
+      rust-dependencies:
+        patterns:
+          - "*"
+
+  - package-ecosystem: github-actions
+    directory: /
+    schedule:
+      interval: monthly
+    groups:
+      github-actions:
+        patterns:
+          - "*"