Drop Python 3.7 support

[kumaraditya303]

Numpy has already dropped support for Python 3.7 https://github.com/numpy/numpy/blob/a1b5d443c375f9b63a415027da66f3d729cd59b5/setup.py#L410 so playwright can also drop support for it as most packages follow numpy release support. Doing this would also remove certain 3.7 specific hacks/workarounds.

[mxschmitt]

I checked various famous libraries, here is a brief investigation:

• Tensorflow: Python 3.6+ (https://www.tensorflow.org/install/pip)
• Pytorch, Python 3.6.2+ (https://github.com/pytorch/pytorch/blob/master/setup.py)
• Django 3.6+ (https://docs.djangoproject.com/en/3.2/faq/install/#what-python-version-can-i-use-with-django)
• Flask, 3.7+ (https://flask.palletsprojects.com/en/2.0.x/installation/)

I would wait a bit more to drop the Python 3.7 support.

[kumaraditya303]

• Pandas https://github.com/pandas-dev/pandas/blob/master/setup.cfg
• Scipy https://github.com/scipy/scipy/blob/master/setup.py

Overall if numpy dropped support then all other packages will drop support for 3.7 as per their schedule.

Some benefits :

• Better process management as newer versions have threadedchildwatcher fixes fix: fix process handling bugs #966

• Better Syntax for typing, no more quotes for some classes

• Better typing support, will not require typing-extensions to be installed at all.

• Walrus operator

[mxschmitt]

aiohttp and uvloop require Python >= 3.7, so they are on the same minimum version as we are.

[kumaraditya303]

aiohttp and uvloop require Python >= 3.7, so they are on the same minimum version as we are.

Sorry copy & paste error.

[kumaraditya303]

@mxschmitt fixed list

[mxschmitt]

Closing for now, lets keep supporting Python 3.7 for now.