dependabot: group GHA updates (#855)

Signed-off-by: William Woodruff <william@trailofbits.com>

Author: woodruffw

.github/dependabot.yml

@@ -12,10 +12,18 @@ updates:
       interval: daily
     open-pull-requests-limit: 99
     rebase-strategy: "disabled"
+    groups:
+      actions:
+        patterns:
+          - "*"
 
   - package-ecosystem: github-actions
     directory: .github/actions/upload-coverage/
     schedule:
       interval: daily
     open-pull-requests-limit: 99
     rebase-strategy: "disabled"
+    groups:
+      actions:
+        patterns:
+          - "*"