dependabot: batch updates

Rather than endless rebases, just batch all go updates to once a week.

Signed-off-by: Casey Callendrello <c1@caseyc.net>

.github/dependabot.yml

@@ -17,3 +17,7 @@ updates:
     directory: "/"  # Location of package manifests
     schedule:
       interval: "weekly"
+    groups:
+      golang:
+        patterns:
+          - "*"