Cirrus CI: Fix wrong name for PyPI GitPython module

.cirrus.yml

@@ -4,8 +4,8 @@ container:
 code_check_task:
     pip_cache:
         folder: ~/.cache/pip
-        populate_script: pip install pylint requests yapf git
-    pip_install_script: pip install pylint requests yapf git
+        populate_script: pip install pylint requests yapf GitPython
+    pip_install_script: pip install pylint requests yapf GitPython
     buildkit_script:
         - python3 -m yapf --style '.style.yapf' -e '*/third_party/*' -rpd buildkit
         - ./devutils/pylint_buildkit.py --hide-fixme