ci: add PR title validation

.github/labeler.yml

@@ -0,0 +1,15 @@
+# see https://github.com/srvaroa/labeler
+version: 1
+issues: False
+labels:
+- label: "bug"
+  title: "^fix(\\(.*\\))?:.*"
+- label: "dependencies"
+  title: "^deps(\\(.*\\))?:.*"
+- label: "documentation"
+  title: "^docs(\\(.*\\))?:.*"
+- label: "enhancement"
+  title: "^(enh|feat)(\\(.*\\))?:.*"
+- label: "work-in-progress"
+  title: "^WIP:.*"
+  mergeable: false