* add more tests
* add tests to raise coverage
* more tests, bump coverage to 73
* fix up icon_button test
* fix darglint for app.py
* fix utcnow usage warning
* set threshold to 72
* fix timestamp
* fix unit tests for linux-redis
* removed commented code and put a TODO
* pass lang and custom_attrs from app to html root
* fix some pre-commit errors and try adding lang
* fix tests
* really fix test
* cleanup with @benedikt-bartscher
* fix props and tests
* use str instead of var
* change typing of html_custom_attrs to not allow Vars
