Fix: OperationalError('unable to open database file')

[ValueRaider]

Fix #1694
Also refactored timezone caching, and improve testing to detect cache folder issues.

[CharlesFr]

We're getting this seemingly related error on 0.2.30, any ideas?

File "/usr/local/lib/python3.10/site-packages/quantstats/__init__.py", line 26, in <module>
    from . import stats, utils, plots, reports
  File "/usr/local/lib/python3.10/site-packages/quantstats/stats.py", line 27, in <module>
    from . import utils as _utils
  File "/usr/local/lib/python3.10/site-packages/quantstats/utils.py", line 24, in <module>
    import yfinance as _yf
  File "/usr/local/lib/python3.10/site-packages/yfinance/__init__.py", line 23, in <module>
    from .ticker import Ticker
  File "/usr/local/lib/python3.10/site-packages/yfinance/ticker.py", line 29, in <module>
    from .base import TickerBase
  File "/usr/local/lib/python3.10/site-packages/yfinance/base.py", line 38, in <module>
    from . import utils
  File "/usr/local/lib/python3.10/site-packages/yfinance/utils.py", line 991, in <module>
    class _KV(_peewee.Model):
  File "/usr/local/lib/python3.10/site-packages/yfinance/utils.py", line 995, in _KV
    class Meta:
  File "/usr/local/lib/python3.10/site-packages/yfinance/utils.py", line 996, in Meta
    database = _DBManager.get_database()
  File "/usr/local/lib/python3.10/site-packages/yfinance/utils.py", line 953, in get_database
    cls._initialise()
  File "/usr/local/lib/python3.10/site-packages/yfinance/utils.py", line 972, in _initialise
    _os.mkdir(cls._cache_dir)
FileNotFoundError: [Errno 2] No such file or directory: '/home/django/.cache/py-yfinance'"

[ValueRaider]

@CharlesFr #1700 (comment)