5.0.9

In general, better Python 3.9 support.

• Improve 3.9 IS_OP and CONTAINS_OP operand formatting
• Correct disassembly of 3.9 bytecode from other bytecode
• Accept 3.9.3 and 3.9.4 as a valid 3.9 version
• Accept 3.8.9 as a valid 3.8 version