Fix some edge cases on Windows

Thank you @Javagedes for the PR!

Add parse_gitignore_str() so you don't need a file

Thank you @tewalds for the PR (#74)!

Fix ValueError on some symlinks

Thank you @matthieumarrast for the PR!

Add support and testing for Python 3.12

Thank you @ericwb for the PR!

Correct behavior with regards to symlinks

Thank you @ruancomelli for the PR.

Multiple parsing improvements

Thank you @jherland!

• Fix lack of implicit anchoring of patterns to directory separators (#58)
• Fix multi-asterisks that fall outside of the special cases (#57)
• Fix "a/**/b" matching "a/bb" (#56)

Fix two incorrect parsing behaviors

Thank you @jherland!

• Fix patterns with leading exclamation marks
• Fix pattern with slash in range

Several modernization improvements

Great PRs by @ruancomelli:

• #48
• #49
• #50
• #51

Also fixes a depreciation warning (#42).

Thank you @ruancomelli!

Improve performance for negation rules

Thank you @ruancomelli for the PR!

Fix directory rule matching similar files

Fixes #45. Thank you @PidgeyBE for the PR!