Cairole - 2

• Sync version number with corresponding uncompile6 version. The big change in 3.7.7 was using xdis >= 6.x
• use expr_stmt instead of call_stmt when that is what is meant
• remove float version tests
• better, but not perfect, list .. if comprehensions
• PyPy 3.8 testing support
• Start PyPy 3.7 and PyPy 3.8 decompilation support