v1.3.0 - Stricter Parsing

In this release I fixed some bugs where the parser was being too lenient and allowing invalid input durations. Thanks to @jrdouceur for creating this issue pointing out that the parser would allow durations that were missing the period section identifier T0S.

I noticed while fixing this that the parser would also allow improperly placed negative signs P-T0S and multiple period sections PT0SP0D. Both of those bugs have been fixed too.

Also a lot of gratitude to @ccoVeille for contributing github actions, style fixes, and reviews!

Code quality and issue turnaround time for this repository will be better now. :)