1.4.9

Fixes:
* Fixed Windows build for 64-bit Python 3.9 on AppVeyor CI.

Changes:
* The SysEx reception buffer size for the Windows MM backend was changed from 8096 to 8196.
* Synced with upstream RtMidi (3dc525b, fixes #89).

---

Note: DO NOT use the source code archives attached below under "Assets"!

The official source distribution is always the one uploaded to the python-rtmidi's Python Package Index page.