[CI] Add workflow to run python unittests

To ensure that they do not regress if someone forgets to run them locally.
This is similiar to the check-ci.yml worfklow in the monorepo.

Pull Request: llvm#607

Author: boomanaiden154

.github/workflows/ci-python-unit.yml

@@ -0,0 +1,29 @@
+name: CI Python Unit Tests
+
+permissions:
+  contents: read
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  run_tests:
+    name: Check CI Python Unit Tests
+    if: github.repository_owner == 'llvm'
+    runs-on: ubuntu-24.04
+    steps:
+    - uses: actions/checkout@v4
+    - uses: actions/setup-python@v6
+      with:
+        python-version: '3.13'
+        cache: 'pip'
+    - name: Install Python Dependencies
+      run: |
+        pip3 install -r premerge/buildbot/requirements.lock.txt
+        pip3 install -r premerge/advisor/requirements.lock.txt
+        pip3 install pytest==8.4.1
+    - name: Run Tests
+      run: pytest premerge/ zorg/buildbot/builders/annotated/premerge/dispatch_job_test.py