Update pygithub from 1.43.7 to 1.43.8

Author: pyup-bot

dev-requirements.txt

@@ -12,7 +12,7 @@ mypy==0.711  # Type checking
 pip_check_reqs==2.0.3
 pydocstyle==3.0.0  # Lint docstrings
 pyenchant==2.0.0  # Bindings for a spellchecking sytem
-pygithub==1.43.7
+pygithub==1.43.8
 Pygments==2.4.2
 pylint==2.3.1  # Lint
 pyroma==2.5  # Packaging best practices checker