Support for PHP 8.1 enums + fixes

feat!: support for PHP 8.1; use of PHP Enums
feat!: drops support for ext-pthreads
feat: adds loop's $until parameter to be able too finish loop by some specified $dateTime
fix: prevent Undefined offset for Ticks with Intervals <1s
test: implemented unit tests for Ticker::loop()

Support for PHP 8.1 enums

v3.0.0-beta

feat!: added support for PHP 8.1 enums

High resolution ticks

• implemented high-res ticks for 10th-10000th parts of a second
• fixed sleep/uSleep auto-determine feature

v2.0.0

Implemented support for threading and several other enchancements

Ticker beta release

v1.0.0-beta

code cleanups