Add py310 for support Python 3.10

[heavenshell]

Add Python 3.10 🙏

py310 run-test-pre: PYTHONHASHSEED='2720618943'
py310 run-test: commands[0] | python test/test_autopep8.py
........../tmp/autopep8/autopep8.py:198: PendingDeprecationWarning: lib2to3 package is deprecated and may not be able to parse Python 3.10+
  from lib2to3.pgen2 import tokenize as lib2to3_tokenize
..........--indent-size must be greater than 0........................[file:/var/folders/wk/pygq97bn6ssffysmw10b3xb80000gn/T/autopep8testt2q37xvy/foo.py]
--->  0 issue(s) to fix {}
...............s......................................s.........................s...................................................................................................................................................................................................................................................................................................................................................................s.........................................................................................................
----------------------------------------------------------------------
Ran 586 tests in 25.274s

OK (skipped=4)
py310 run-test: commands[1] | python test/acid.py --aggressive test/example.py
--->  Testing with /tmp/autopep8/test/example.py
/tmp/autopep8/.tox/py310/bin/Python /tmp/autopep8/autopep8.py --max-line-length=79 --ignore= /tmp/autopep8/test/example.py --aggressive
py310 run-test: commands[2] | python test/acid.py --compare-bytecode test/example.py
--->  Testing with /tmp/autopep8/test/example.py
/tmp/autopep8/.tox/py310/bin/python /tmp/autopep8/autopep8.py --max-line-length=79 --ignore=E71,E721,W /tmp/autopep8/test/example.py
/var/folders/wk/pygq97bn6ssffysmw10b3xb80000gn/T/tmprjoo488f.py:70:1: E704 multiple statements on one line (def)
def func_oneline(): print(1)
^
autopep8 did not completely fix /tmp/autopep8/test/example.py
___________________________________ summary ____________________________________
  py310: commands succeeded
  congratulations :)

[codecov-commenter]

Codecov Report

Merging #615 (95351d0) into master (49dbc74) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #615   +/-   ##
=======================================
  Coverage   97.80%   97.80%           
=======================================
  Files           1        1           
  Lines        2368     2368           
=======================================
  Hits         2316     2316           
  Misses         52       52           

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[heavenshell]

Thank you!