fix type error in queue.hpp, improve distributability and documentation

[keyan3]

Code changes:

• tiny change in queue.hpp that allows gosdt c++ code to compile on clang with versions of tbb after '2020_U3' (solves this issue i opened previously)

Distribution:

• added a Github Actions workflow which uses cibuildwheel to build wheels so the gosdt c++ extension doesn't need to be built on every users machine. This also prevents users from having to install the dependencies like tbb, etc.
• added a requirements.txt that makes installing the dependencies for the local python wrapper easier
• add MIT license (i can change this to any other license you'd like, just let me know)
• increment version number

Documentation:

• in README, distinguish between the local python wrapper and an sklearn-style wrapper that we have included in the imodels interpretable ML package
• add installation test notebook which trains and tests on COMPAS dataset
• provide more package information in setup.py for users who install gosdt via pip (kept jimmy.projects.lin as contact email, let me know if this should be updated)

let me know if you have any questions or concerns!