v0.7.0 – Optional durations, Chinese translations

[0.7.0] - 2020-11-06

• Made the duration field optional, and altered it from PositiveIntegerField to FloatField. If you rely on integer output of duration in templates use {{ media.duration|floatformat:"0" }} instead of {{ media.duration }} to restore the previous behavior (#100, #106, #108, #110). Thanks to @thenewguy!
• Fixed deprecation warnings with Django 3.0 (#94, #109).
• Excluded tests folder from published package’s sdist (#107)).
• Added Chinese (China) translations (#114). Thanks to @Dannykey and @BrianXu20
• Removed declared support for Python 3.5, Wagtail 2.8, Wagtail 2.9 (#116)
• Added declared support for Python 3.9, Wagtail 2.11, Django 3.1 (#116)