Remove any syntax required for python < 3.8

[WhyNotHugo]

> find . -iname "*.py" -exec pyupgrade --py38-plus {} \;

[mauritsvanrees]

Looks okay. Thanks. I guess compat.py can be removed now, like you did on your PR #327.
Waiting on an answer to my recent question there.

[WhyNotHugo]

It can likely be remove. This PR is purely autogenerated, hence the reason to keep it all separate.

[niccokunzmann]

I would wait until #368 is merged so we know if we want to drop Python 3.7 already.

find . -iname "*.py" -exec pyupgrade --py38-plus {} ;

Cool! That might also work for Python 3.7 if needed. Thanks for showing that, I did not know it existed!

[WhyNotHugo]

If you want to keep 3.7 around for now, I can just redo the PR using:

find . -iname "*.py" -exec pyupgrade --py37-plus {} \;

[niccokunzmann]

@WhyNotHugo #368b has been merged. Would you like to make a new PR for py37?

[WhyNotHugo]

As far as I can tell, master only supports 3.8:

• https://github.com/collective/icalendar/blob/master/setup.py#L39
• https://github.com/collective/icalendar/blob/master/setup.py#L55

I've created a PR for the 4.x branch, see: #384

[niccokunzmann]

@WhyNotHugo thanks for your effort - I just ran the tests for Python3.7 and it works with this PR. I think, you can close #384 and we will merge this one...

~/icalendar$ git merge niccokunzmann-test-py37
Auto-merging setup.py
Merge made by the 'ort' strategy.
 .github/workflows/tests.yml | 1 +
 CHANGES.rst                 | 2 +-
 setup.py                    | 3 ++-
 tox.ini                     | 2 +-
 4 files changed, 5 insertions(+), 3 deletions(-)
sabin@schneidebrett:~/icalendar$ tox -e py37
/home/sabin/icalendar/.tox/py37/lib/python3.7/site-packages/setuptools/config/setupcfg.py:463: SetuptoolsDeprecationWarning: The license_file parameter is deprecated, use license_files instead.
  warnings.warn(msg, warning_class)
py37 develop-inst-nodeps: /home/sabin/icalendar
py37 installed: attrs==22.1.0,coverage==6.4.4,-e git+ssh://git@github.com/niccokunzmann/icalendar@c22c64f86ed0807ae4667dd4681051f555d4e450#egg=icalendar,importlib-metadata==4.12.0,iniconfig==1.1.1,packaging==21.3,pluggy==1.0.0,py==1.11.0,pyparsing==3.0.9,pytest==7.1.2,python-dateutil==2.8.2,pytz==2022.2.1,six==1.16.0,tomli==2.0.1,typing_extensions==4.3.0,zipp==3.8.1
py37 run-test-pre: PYTHONHASHSEED='983511143'
py37 run-test: commands[0] | coverage run --source=src/icalendar '--omit=*/tests/*' --module pytest
============================= test session starts ==============================
platform linux -- Python 3.7.13, pytest-7.1.2, pluggy-1.0.0
cachedir: .tox/py37/.pytest_cache
rootdir: /home/sabin/icalendar, configfile: setup.cfg
collected 97 items                                                             

src/icalendar/tests/test_encoding.py ....                                [  4%]
src/icalendar/tests/test_fixed_issues.py .....................           [ 25%]
src/icalendar/tests/test_icalendar.py .........                          [ 35%]
src/icalendar/tests/test_multiple.py .                                   [ 36%]
src/icalendar/tests/test_property_params.py .......                      [ 43%]
src/icalendar/tests/test_recurrence.py ..                                [ 45%]
src/icalendar/tests/test_time.py ..                                      [ 47%]
src/icalendar/tests/test_timezoned.py ........                           [ 55%]
src/icalendar/tests/test_unit_cal.py ...........                         [ 67%]
src/icalendar/tests/test_unit_caselessdict.py ....                       [ 71%]
src/icalendar/tests/test_unit_parser_tools.py ..                         [ 73%]
src/icalendar/tests/test_unit_prop.py .........................          [ 98%]
src/icalendar/tests/test_unit_tools.py .                                 [100%]

============================== 97 passed in 1.66s ==============================
py37 run-test: commands[1] | coverage report
Name                                Stmts   Miss  Cover
-------------------------------------------------------
src/icalendar/__init__.py               5      0   100%
src/icalendar/cal.py                  332      8    98%
src/icalendar/caselessdict.py          62      5    92%
src/icalendar/cli.py                   35     35     0%
src/icalendar/compat.py                 1      0   100%
src/icalendar/parser.py               202      6    97%
src/icalendar/parser_tools.py          20      0   100%
src/icalendar/prop.py                 562     61    89%
src/icalendar/timezone_cache.py         1      0   100%
src/icalendar/tools.py                 18      0   100%
src/icalendar/windows_to_olson.py       1      0   100%
-------------------------------------------------------
TOTAL                                1239    115    91%
py37 run-test: commands[2] | coverage html
Wrote HTML report to htmlcov/index.html
___________________________________ summary ____________________________________
  py37: commands succeeded
  congratulations :)
sabin@schneidebrett:~/icalendar$ git status
On branch WhyNotHugo-py38