v1.13.0 - Under the hood

Internal improvements

• libtmux updated from v0.12 to v0.14 #790
• Add doctest w/ pytest + doctest, via #791.
• Added basic mypy type annotations via #786

Automated PR list

• libtmux v0.14 by @tony in #790
• libtmux v0.13 (mypy annotations) by @tony in #789
• Basic doctests by @tony in #791
• docs: Fix a few typos by @timgates42 in #785
• Basic mypy typings by @tony in #786

Full Changelog: v1.12.1...v1.13.0