Httpy

**:heavy_check_mark: This update is _internal_**
That means the API didn't change in this update, so you don't need to read this.

Things that are new:

- Added `Expires` header parsing for better caching.

:warning: Please read the description carefully, as it may affect your experience with `httpy`
BIG WINDOWS BUGFIX: obviously ASCII control characters can't be in Windows file paths, so httpy couldn't create cache files on Windows. :window:
Also fixed up `CaseInsensitiveDict` behavior.
And only `GET` and `HEAD` methods are cacheable because MDN (and RFC too I guess) says so.
That's all.
Things that are new:

- cache file paths changed. Now `://` is replaced with `\xfe` ( þ in Unicode) and `/` with `\xff`
- CaseInsensitiveDict now assigns to original too, and it has `update()` method coded internally, does not rely on inheritance from `dict`.
- You now can cache only `GET` and `HEAD` methods

Further fixes regarding caching.
Things that are new:
- `CacheFile.__init__` now treats `method_l` as `int16`

Major bugfix regarding caching

Things that are new:
- Cache files now contain also the request method
- `method` attribute of `Response`

New PyPI page
Things that are new:
- Badges on PyPI page
- Autoload of README.md in setup.py

Major bugfix regarding weird behavior of SSL in PyPy , see https://stackoverflow.com/questions/73108842/
Things that are new:

- `context` is now `ssl._create_default_http_context()`