Tag version 0.1.5

Update backend dependencies

* gunicorn 21 -> 23
* pygments 2.6 -> 2.18
* beautifulsoup4 4.11 -> 4.12
* pytest 7.4 -> 8.3
* watchdog 3.0 -> 6.0

Additionally, drop integration tests for Python 3.8 which is EOL.

Bump flake8 version to fix false E231 error

Reference: PyCQA/pycodestyle#1148

bump to version 0.1.2 to prepare for release