Release v3.0.0

[v3.0.0]

Added

• Add ANN402 for the presence of type comments

Changed

• Python 3.8.1 is now the minimum supported version
• Flake8 v5.0 is now the minimum supported version

Removed

• Remove support for PEP 484-style type comments
  • See: https://mail.python.org/archives/list/typing-sig@python.org/thread/66JDHQ2I3U3CPUIYA43W7SPEJLLPUETG/
  • See: python/mypy#12947
• Remove ANN301