Homebrew installing Python versions changes what `python3` is. Packag…

…es went missing.

Deploy for Python 3.9 (Windows and Linux only)

Recognizing Python 3.9, which is now the default in Homebrew on macOS

The BioFormats JAR file is required for building, my bad

Updates for Travis -- macOS Homebrew now has Python 3.8 as default ve…

…rsion.

Bump patchlevel

bugfix