Support Python 3.10

[laike9m]

Python 3.10 changelog

Bytecode changes can be found by viewing magic number change history

• Make 'annotations' future by default bpo-38605
  Undo making 'annotations' future by default bpo-38605
• New line number table format -- PEP 626 bpo-42246: Bump magic number. python/cpython#23245
  • We rely on dis.findlinestarts to determine lineno, which is already using code.co_lines internally (see https://bugs.python.org/issue44875). So we're good.
• Function annotation for MAKE_FUNCTION is changed from dict to tuple bpo-42202
  • This should not affect Cb. It only changes how annotation is stored (from map to tuple), which are are all consts.
• ❓ RERAISE restores f_lasti if oparg != 0 bpo-42246
  • Not sure if this affects anything, for now assume no. Will come to it if we hit any issues.
• PEP 634: Structural Pattern Matching bpo-42128
• Use instruction offsets (as opposed to byte offsets)
• Add GEN_START bytecode bpo-43683
• Safer line number table handling bpo-42739

Other bytecode related changes:

• bpo-41670: Remove outdated predict macro invocation. (GH-22026)

[victorjzsun]

Note: Python3.10 uses co_lines instead of co_lnotab for source code line numbers
There might be changes to source code linenos for events

[laike9m]

Currently the code does not use co_lnotab directly.

[laike9m]

I tried running the test suite under Python 3.10 rc2. Many tests failed as expected. Will try to fix them.

[laike9m]

Right now blocked by ultrajson/ultrajson#482. We need ujson 4.2.0 to support 3.10, but ujson 4.2.0 needs installer 0.3.0 (released in a few days) to be successfully installed. So we can just wait.

To be more specific, we need a pre-built ujson wheel for Python 3.10, otherwise GitHub Actions will fail to build it.

This is fixed.