ci: Trigger checks on adding to merge queue (#28)

Author: jimmidyson

.github/workflows/checks.yml

@@ -12,6 +12,9 @@ on:
       - opened
       - synchronize
       - reopened
+  merge_group:
+    types:
+      - checks_requested
 
 permissions:
   contents: read

.github/workflows/stacked-prs.yml

@@ -13,6 +13,9 @@ permissions:
 on:
   pull_request_target:
     types: [opened, edited, reopened, synchronize]
+  merge_group:
+    types:
+      - checks_requested
 
 jobs:
   check: