[CI] Trigger slow build on PR.

Author: vyazelenko

.github/workflows/ci.yml

@@ -10,6 +10,7 @@ on:
     types: [opened, synchronize]
     branches:
       - master
+      - 'release/**'
 
 concurrency:
   group: ci-${{ github.workflow }}-${{ github.ref }}

.github/workflows/slow.yml

@@ -7,6 +7,11 @@ on:
       - '**'
   schedule:
     - cron: '0 12 * * *'
+  pull_request:
+    types: [opened, synchronize]
+    branches:
+      - master
+      - 'release/**'
 
 concurrency:
   group: slow-${{ github.workflow }}-${{ github.ref }}