ci: Add "build" label type to accepted PR titles (#3541)

# Overview
This PR adds the "build" label type to the accepted "Conventional Types"
labels that are accepted.

This is specifically for build-related things (e.g., `Makefile`s). The
existing labels did not really address certain types of possible
changes, in my opinion.

.github/workflows/pr-labeller.yml

@@ -16,5 +16,5 @@ jobs:
     - name: PR Conventional Commit Validation
       uses: ytanikin/[email protected]
       with:
-        task_types: '["feat","fix","docs","test","ci","refactor","perf","chore","revert"]'
+        task_types: '["feat","fix","docs","test","ci","refactor","perf","chore","revert","build"]'
         add_label: 'true'