- update to 2.5.2:
* PR 489 - PR: Fix detecting Matplotlib backend for its 3.9.0
version

* Fix misplaced section in changelog, by @ccordoba12
* PR 291 - PR: Pass adding breakpoint on ValueError,
* PR 266 - PR: Add exception for quit and exit in SpyderPdb,
* PR 262 - PR: Avoid infinite hang when quitting external
* Issue 247 - Remove from warning that future versions of
Spyder will give an error when using non-Python syntax
* PR 253 - PR: Extend sys.path with paths that come from
* PR 252 - PR: Use frame locals when evaluating code in
* PR 251 - PR: Catch errors when trying to get the len of
* PR 250 - PR: Show size of objects correctly, if they
* PR 246 - PR: Allow sorting with custom sorting key, by
* PR 244 - PR: Set multiprocessing ORIGINAL_DIR at startup,
* PR 243 - PR: Allow leading indents in cells, by
- remove unused python2 requirements
- [PR 21](https://github.com/spyder-ide/spyder-kernels/pull/21) - PR: Add AUTHORS.txt in MANIFEST.in to include in package