Handle closing connection when event loop is closed

[alisaifee]

Pull Request check-list

• Do tests and lints pass with this change?
• Do the CI tests pass with this change (enable it first in your forked repo and wait for the github action build to finish)?
• Is the new or changed code fully tested?
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?
• Is there an example added to the examples folder (if applicable)?

Description of change

Improve the connection cleanup logic in AbstractConnection by adding a try-except block around the .close() call on the writer to protect against scenarios where the event loop is already closed.

Given an example use case:

import asyncio
import valkey.asyncio

client = valkey.asyncio.Redis.from_url("redis://localhost:7379")
asyncio.run(client.ping())

The following traceback is noted after the process exists:

Exception ignored in: <function AbstractConnection.__del__ at 0x10519e340>
Traceback (most recent call last):
  File "<...>/valkey-py/valkey/asyncio/connection.py", line 243, in __del__
  File "<...>/valkey-py/valkey/asyncio/connection.py", line 250, in _close
  File "<...>/python/3.12.0/lib/python3.12/asyncio/streams.py", line 343, in close
  File "<...>/python/3.12.0/lib/python3.12/asyncio/selector_events.py", line 1206, in close
  File "<...>/python/3.12.0/lib/python3.12/asyncio/selector_events.py", line 871, in close
  File "<...>/python/3.12.0/lib/python3.12/asyncio/base_events.py", line 772, in call_soon
  File "<...>/python/3.12.0/lib/python3.12/asyncio/base_events.py", line 519, in _check_closed
RuntimeError: Event loop is closed