Tqdm

- update tests (1108)
+ make pre-commit `pytest` quicker
+ switch pre-commit from `make` to `python`
+ add and update (auto) formatters & CI (1108, 1093)
- update contributing guidelines (1108)
+ fix formatting
+ test dependencies (1109)
- update `.gitignore`
- fix (auto & manual) formatting
- fix minor detected bugs
- misc build/CI framework upgrades

- fix `(Rolling|Expanding).progress_apply()` on `pandas==1.2.0` (1106)
- minor documentation updates

- fix ASCII notebook export (937, 1035, 1098)
- fix notebook gui-mode extra spaces (433, 479, 550, 935)
- better ETA for early iterations (1101)
- better ETA for wildly varying iteration rates (1102)
- update submodule inheritance
+ `tqdm.gui`
+ `tqdm.notebook`
+ `tqdm.contrib.telegram`
+ `tqdm.contrib.discord`
- documentation updates
- misc code optimisations
- add tests
- framework updates
+ build
+ CI & test
- misc code linting/formatting

- drop `py3.4` (no longer tested) (1091)
- misc CI updates (1091)
+ update `snap` build & deploy method
+ bot releases

- get rid of `get_new` (1085 <- 1084, 509)
- minor CI framework optimisations

- provide `get_new()` helper for mixed subclasses in nested mode (509)
- fix nested `asyncio` (1074)
+ document async `break` hazard
- add tests
- drop py2.6/3.2/3.3 and distutils (no longer tested)
+ drop py2.6 (502 <- 620, 127)
+ drop `distutils` in favour of `setuptools`/`setup.cfg` (723, 721)
- CI framework overhaul
+ drop appveyor (Windows already tested by GHA)
+ skip `devel` PRs
+ automate linting comments on failure
- use `setuptools_scm` (722)
+ fix & update tests
+ fix & upgrade snap build
+ update CONTRIBUTING docs