PR: Remove BaseTestCase from `testsuite/`

PR: `testsuite/platform.py` conversion to pytest + remove `BaseTestCase`

simplify flake8 config, fix some complaints

we use black since a while, so some stuff does not need to be ignored any more.

fix test_disk_full, fixes #7617

- master branch has different free space requirements from 1.2-maint,
so we now use a 700MB fi...

remove unused methods of BaseTestCase

also: clean up imports / comments

tests: remove usage of environment_variable context manager, fixes #1002

rather use monkeypatch.setenv/delenv.

f'repo={repo_location}' moved to 'cmd' function

Archiver folder - all tests converted from unittest to pytest

BORG_WORKAROUNDS=authenticated_no_key to extract from authenticated repos without key, fixes #7700

This is an emergency workaround for authenticated repos
if the user has lost the borg key.

We c...

parameterized stats_progress and timestamp_parsing tests

automated-local.rst: use GPT UUID for consistent udev rule

Docs: Rewrite `borg check` docs

Fix failing test on OpenBSD

A borgbackup-2.0.0b6 test fails on OpenBSD with the message below.

```
========================...

manifest: move item_keys into config dict, fixes #7710

Properly normalise paths on Windows

doc updates (master)

replace "datetime.utcfromtimestamp" to avoid deprecation warnings with Python 3.12

Fixes #7578