Fixed: Support Python 3.9's changed urllib.parse.urljoin() behavior.
- < py3.9:
furl('wss://slrp.com/').join('foo:1')->'wss://slrp.com/foo:1' - >= py3.9:
furl('wss://slrp.com/').join('foo:1')->'foo:1'
Changed: Drop semicolon query delimiters. See https://bugs.python.org/issue42967.
Changed: Drop support for EOL Python 3.4 and Python 3.5.