Add pyasyncore to mitigate removal of asyncore in PEP 594

Author: simonrob

README.md

@@ -94,7 +94,7 @@ The [plugins branch](https://github.com/simonrob/email-oauth2-proxy/tree/plugins
 
 
 ## Potential improvements (pull requests welcome)
-- Switch to asyncio (asyncore is currently deprecated, but [PEP 594](https://peps.python.org/pep-0594/) will remove it completely in Python 3.12)
+- Switch to asyncio? (asyncore is currently deprecated, but [PEP 594](https://peps.python.org/pep-0594/) will remove it completely in Python 3.12 – currently mitigated by the use of [pyasyncore](https://pypi.org/project/pyasyncore/))
 - Full feature parity on different platforms (e.g., live menu updating; monitoring network status)
 - Clickable account authorisation notifications
 - STARTTLS for IMAP?

requirements.txt

@@ -5,6 +5,9 @@ pystray
 pywebview; sys_platform != 'win32'  # specify platform to avoid double requirement error with older pip versions
 timeago
 
+# provide the previously standard library module `asyncore`, removed in Python 3.12 (https://peps.python.org/pep-0594/)
+pyasyncore; python_version >= '3.12'
+
 # used to improve menu bar interaction, provide native notifications, handle system events and output to unified logging
 pyobjc-framework-Cocoa; sys_platform == 'darwin'
 pyobjc-framework-SystemConfiguration; sys_platform == 'darwin'