version bump 

Merge pull request #10 from shivammathur/ext-xz Fix windows workflow

❌ bye travis 

 change default branch to "main" 

✨ 

Version bumped to v0.1.1. Implemented `xzencode` and `xzdecode`. Refactoring. Wrote more documentation. Configuration can be altered via `php.ini`. Rewrote tests and added tests for new functions. Added `LICENSE.txt`. Updated the header as well. Updated installation instructions.

Added PHPUnit configuration.