Remove an Extra Warning Filter in eventloop.py

[johnzhou721]

The version is smaller than 3.14 in the branch of the customly-defined RubiconEventLoop function, so there's no "deprecations in 3.14" to speak of when creating an event loop policy.

PR Checklist:

• All new features have been tested
• All new features have been documented
• I have read the CONTRIBUTING.md file
• I will abide by the code of conduct

[freakboy3742]

You've misunderstood what is going on here.

Any attempt to instantiate EventLoopPolicy raises a warning in Python 3.13 or earlier, as a pre-warning to users that they need to adapt their code. The implementation of RubiconEventLoop on Python 3.13 and earlier uses the old API (which hasn't been deprecated on Python3.13 and earlier) to reproduce the behavior that will exist o Python 3.14+. If users have invoked RubiconEventLoop(), they've already done the adaptation that will be required to avoid the deprecation in future, so the warning can be silenced.

[johnzhou721]

Sorry. "[H]ave been" meant that it's already done, but forgot that CPython has backports.