protect 1.2.x branch (#331)

diff --git a/.asf.yaml b/.asf.yaml
index 46d95ff..d1b61ad 100644
--- a/.asf.yaml
+++ b/.asf.yaml
@@ -66,6 +66,18 @@
         dismiss_stale_reviews: false
         require_code_owner_reviews: false
         required_approving_review_count: 1
+    1.2.x:
+      required_status_checks:
+        # strict means "Require branches to be up to date before merging".
+        strict: false
+        # contexts are the names of checks that must pass
+        contexts:
+          - Code is formatted
+          - Check headers
+      required_pull_request_reviews:
+        dismiss_stale_reviews: false
+        require_code_owner_reviews: false
+        required_approving_review_count: 1
 
 notifications:
   commits:              commits@pekko.apache.org