ci: only run release checks on release- PRs

.github/workflows/ci.yml

@@ -1,6 +1,7 @@
 name: CI
 
 on:
+  workflow_dispatch:
   pull_request:
   push:
     branches: [main]
@@ -580,6 +581,7 @@ jobs:
     name: Run x86_64 Linux release checks
     runs-on: UbuntuLatest64Cores256GX86
     needs: [lints, build-x86_64-linux]
+    if: contains(github.ref, 'release-')
     permissions:
       id-token: "write"
       contents: "read"