Markdown-katex

- Fix [17][gh_17] rare concurrency issue.

[gh_17]: https://github.com/mbarkhau/markdown-katex/pull/17

- Update KaTeX binaries to v0.15.1
- Fix [13][gh_13]: Don't strip `<p></p>` when using inline syntax for a single equation.

[gh_13]: https://github.com/mbarkhau/markdown-katex/issue/13

- Update KaTeX binaries to v0.13.18

- Fix [8][gh_8]: Math inside admonition
- Update KaTeX binaries to v0.13.11

[gh_8]: https://github.com/mbarkhau/markdown-katex/issue/8

- Update KaTeX binaries to v0.13.6

- Update KaTeX binaries to v0.13.3
- Fix [4][gh_4]: Close file descriptors of Popen
- Add support for blocks with extra backticks

[gh_4]: https://github.com/mbarkhau/markdown-katex/pull/4