Merge pull request #2496 from python-trio/dependabot/pip/platformdirs-2.6.0

Bump platformdirs from 2.5.4 to 2.6.0

Author: pquentin

test-requirements.txt

@@ -77,7 +77,7 @@ pexpect==4.8.0
     # via ipython
 pickleshare==0.7.5
     # via ipython
-platformdirs==2.5.4
+platformdirs==2.6.0
     # via
     #   black
     #   pylint