Also clean tests/.pytest_cache

Otherwise, that cache folder makes it into the release tarball.

Author: ctrueden

bin/clean.sh

@@ -6,4 +6,4 @@ cd "$dir/.."
 find . -name __pycache__ -type d | while read d
   do rm -rfv "$d"
 done
-rm -rfv .pytest_cache build dist src/*.egg-info
+rm -rfv .pytest_cache build dist src/*.egg-info tests/.pytest_cache