Add scripttest.yml

[drew2a]

This PR closes #7093 and partially #7085

The Idea to test scripts in the ./scripts/ folder is simple: run each script for 10s and if there are no errors, then these scripts are considered to be "correct".

For implementing this solution 2 problems need to be solved:

1. To run a script for 10s (solved by adding the timeout action, which is an adapted version of linux timeout command).
2. To make a script fragile. It is necessary because these scripts use the asyncio event loop, and errors raised inside the loop don't kill the process (solved by adding the make_async_loop_fragile function).

The checks run on each PR push by calling the scripptest.yml workflow. The average duration of the check is about 1m.

Also, this PR fixes the pyenv action by using the freshest version from the original repo.

Scripts fixed:

1. run_bandwidth_crawler.py
2. run_exit_node.py
3. disseminator.py
4. seeder.py

Refs:

• https://linuxhint.com/timeout-command-in-linux/
• https://man7.org/linux/man-pages/man1/timeout.1.html
• https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#jobsjob_idstepstimeout-minutes
• https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#environment-files
• https://stackoverflow.com/questions/63641822/run-command-with-timeout-in-github-workflow
• https://gist.github.com/bdombro/f45dc7e16f2ed821d2c5d271302c38ce
• https://docs.python.org/3/library/asyncio-eventloop.html
• https://stackoverflow.com/questions/438894/how-do-i-stop-a-program-when-an-exception-is-raised-in-python
• https://docs.python.org/3/library/logging.html#logging.debug
• https://adamj.eu/tech/2021/10/10/the-many-ways-to-exit-in-python/