[flutter_tools] don't run pub_autoroller on release branches (#106830)

diff --git a/.ci.yaml b/.ci.yaml
index cb0ebce..8c23a46 100644
--- a/.ci.yaml
+++ b/.ci.yaml
@@ -136,6 +136,9 @@
     presubmit: false
     recipe: pub_autoroller/pub_autoroller
     timeout: 30
+    enabled_branches:
+      # Don't run this on release branches
+      - master
     properties:
       tags: >
         ["framework","hostonly"]