Labeler: Add labeler glob patterns for CI

We have a "Category: CI" label in GH issues and PRs, but there is no
labeler rule to automatically mark PRs as such.

This adds a labeler rule to automatically add the "Category: CI" label
if the PR changes _any_ file in:

  - .circleci/*
  - .github/actions/**/*
  - .github/CODEOWNERS
  - .github/setup_hmailserver.php
  - .github/nightly_matrix.php
  - .github/scripts/*
  - .github/scripts/**/*
  - .github/labeler.yml
  - .github/workflows/*

Author: Ayesh

.github/labeler.yml

@@ -20,6 +20,19 @@
         - scripts/**/*
         - win32/build/**/*
 
+"Category: CI":
+  - changed-files:
+      - any-glob-to-any-file:
+          - .circleci/*
+          - .github/actions/**/*
+          - .github/CODEOWNERS
+          - .github/setup_hmailserver.php
+          - .github/nightly_matrix.php
+          - .github/scripts/*
+          - .github/scripts/**/*
+          - .github/labeler.yml
+          - .github/workflows/*
+
 "Extension: bcmath":
   - changed-files:
       - any-glob-to-any-file: