Gcodeparser

Fix type hinting for Python 3.9

**Full Changelog**: https://github.com/AndyEveritt/GcodeParser/compare/0.2.3...0.2.4

Improve type hinting & CI

Add additional test for multiple gcodes on the same line

What's Changed
* 'split_params' now handles parameter values prefixed with a '+' sign. by dalibor-frivaldsky in https://github.com/AndyEveritt/GcodeParser/pull/8
* Add github actions

New Contributors
* dalibor-frivaldsky made their first contribution in https://github.com/AndyEveritt/GcodeParser/pull/8

**Full Changelog**: https://github.com/AndyEveritt/GcodeParser/compare/v0.1.1...0.2.0