Group dependabot PRs (#442)

Author: ranile

.github/dependabot.yml

@@ -1,18 +1,28 @@
----
 version: 2
 updates:
   - package-ecosystem: "cargo"
     directory: "/"
     schedule:
       interval: "weekly"
       day: "friday"
+    open-pull-requests-limit: 2
+    groups:
+       cargo-deps:
+          patterns:
+            - "*"
 
   - package-ecosystem: "npm"
     directory: "/website"
     schedule:
       interval: "monthly"
+    target-branch: "master"
+    groups:
+       website-deps:
+          patterns:
+            - "*"
 
   - package-ecosystem: "github-actions"
     directory: "/"
     schedule:
       interval: "monthly"
+    target-branch: "master"