Soupsieve

- **NEW**: Officially support Python 3.10.
- **NEW**: Add static typing.
- **NEW**: `:has()`, `:is()`, and `:where()` now use use a forgiving selector list. While not as forgiving as CSS might
be, it will forgive such things as empty sets and empty slots due to multiple consecutive commas, leading commas, or
trailing commas. Essentially, these pseudo-classes will match all non-empty selectors and ignore empty ones. As the
scraping environment is different than a browser environment, it was chosen not to aggressively forgive bad syntax and
invalid features to ensure the user is alerted that their program may not perform as expected.
- **NEW**: Add support to output a pretty print format of a compiled `SelectorList` for debug purposes.
- **FIX**: Some small corner cases discovered with static typing.

- **FIX**: Fix an issue with namespaces when one of the keys is `self`.

- **NEW**: `:link` and `:any-link` no longer include `<link>` due to a change in the level 4 selector specification. This actually yields more sane results.
- **FIX**: BeautifulSoup, when using `find`, is quite forgiving of odd types that a user may place in an element's attribute value. Soup Sieve will also now be more forgiving and attempt to match these unexpected values in a sane manner by normalizing them before compare. (212)

- **NEW**: Officially support Python 3.9.
- **NEW**: Drop official support for Python 3.5.
- **NEW**: In order to avoid conflicts with future CSS specification changes, non-standard pseudo classes will now start with the `:-soup-` prefix. As a consequence, `:contains()` will now be known as `:-soup-contains()`, though for a time the deprecated form of `:contains()` will still be allowed with a warning that users should migrate over to `:-soup-contains()`.
- **NEW**: Added new non-standard pseudo class `:-soup-contains-own()` which operates similar to `:-soup-contains()` except that it only looks at text nodes directly associated with the currently scoped element and not its descendants.
- **FIX**: Import `bs4` globally instead of in local functions as it appears there are no adverse affects due to
circular imports as `bs4` does not immediately reference `soupsieve` functions and `soupsieve` does not immediately reference `bs4` functions. This should give a performance boost to functions that had previously included `bs4` locally.

- **FIX**: Remove unused code.

- **NEW**: `SelectorSyntaxError` is derived from `Exception` not `SyntaxError`.
- **NEW**: Remove deprecated `comments` and `icomments` from the API.
- **NEW**: Drop support for EOL Python versions (Python 2 and Python < 3.5).
- **FIX**: Corner case with splitting namespace and tag name that have an escaped `|`.