Steps to Reproduce

1. Set up virtualenv using python3 -m venv on a 64-bit machine.
2. Initialize an application object using telegram.ext.ApplicationBuilder:

from telegram.ext import ApplicationBuilder
def main() -> None:
    application = ApplicationBuilder().token("TOKEN").build()

if __name__ == "__main__":
    main()

4. Run the bot in virtualenv and it will give a warning messgae like PTBUserWarning: `Application` instances should be built via the `ApplicationBuilder`.

Expected behaviour

The warning message shouldn't be given since ApplicationBuilder is being used.

Actual behaviour

$ python test.py 
../venv/lib64/python3.11/site-packages/telegram/ext/_applicationbuilder.py:292: 
PTBUserWarning: `Application` instances should be built via the `ApplicationBuilder`.
  ] = DefaultValue.get_value(  # pylint: disable=not-callable

Operating System

Fedora Linux 37 (Server Edition)

Version of Python, python-telegram-bot & dependencies

python-telegram-bot 20.0
Bot API 6.4
Python 3.11.1 (main, Dec  7 2022, 00:00:00) [GCC 12.2.1 20221121 (Red Hat 12.2.1-4)]

Relevant log output

No response

Additional Context

I believe this is caused by comparing a resolved path with an unresolved path here.

In my case, it finds ../venv/lib/python3.11/site-packages/telegram/ext/_applicationbuilder.py not equal to ../venv/lib64/python3.11/site-packages/telegram/ext/_applicationbuilder.py, the directory lib64 being a symlink to lib.

A quick (maybe not final) fix is to modify stack.py so that was_called_by always resolves paths from frame:

    while frame.f_back:
        frame = frame.f_back
        if Path(frame.f_code.co_filename).resolve() == caller:
            return True

I have tested it and the warning no longer appears.