Including changes like,
- loose eg flagging in various test emedded `trio.open_nursery()`s.
- changes to eg handling (like using `except*`).
- added `debug_mode` integration to tests that needed some REPLin
in order to figure out appropriate updates.
- `trio_typing` is nearly obsolete since `trio >= 0.23`
- `exceptiongroup` is built-in to python 3.11
- `async_generator` primitives have lived in `contextlib` for quite
a while!