Description:

Python 3.5 has reached End-Of-Life on the 13th of September, deprecating this could open up synapse to (for example):

• f-string literals (Convert all string concatenations and brace-formatting to f-string formatting #8332)
• Variable typing annotations (Type-annotate all function arguments and internal variables #8351)
• Async generators
• Async list literals (or "comprehensions")

(3.6 release notes)