Trigger release bots on branches of the form major.minor.patch

We use these for AOSP release branches

Change-Id: I14aa8efb5d6f21665702f7658e5bc280f3127f7d
diff --git a/infra/config/global/luci-scheduler.cfg b/infra/config/global/luci-scheduler.cfg
index f7f3305..eb725d9 100644
--- a/infra/config/global/luci-scheduler.cfg
+++ b/infra/config/global/luci-scheduler.cfg
@@ -59,7 +59,7 @@
   gitiles: {
     repo: "https://r8.googlesource.com/r8"
     # Version branches are named d8-x.y (up until d8-1.5) or just x.y (from 1.6)
-    refs: "regexp:refs/heads/(?:d8-)?[0-9]+\\.[0-9]+"
+    refs: "regexp:refs/heads/(?:d8-)?[0-9]+\\.[0-9]+(\\.[0-9]+)?"
     path_regexps: "src/main/java/com/android/tools/r8/Version.java"
   }
   triggers: "archive_release"