v0.8.0 — Type annotations; drop pre-Python 3.6

• Drop support for Python 2.7, 3.4, and 3.5
• Support Python 3.9
• ensure_ascii parameter added to PropertiesFile.dump() and PropertiesFile.dumps()
• Bugfix: When parsing XML input, empty <entry> tags now produce an empty string as a value, not None
• Added type annotations
• Properties and PropertiesFile no longer raise TypeError when given a non-string key or value, as type correctness is now expected to be enforced through static type checking
• The PropertiesElement classes returned by parse() are no longer subclasses of namedtuple, but they can still be iterated over to retrieve their fields like a tuple