fix

Author: Tieqiong

.github/workflows/osx64.yml

@@ -41,7 +41,7 @@ jobs:
           conda info
           conda install --file requirements/test.txt
           conda install numpy diffpy.utils matplotlib-base
-          conda install --solver=classic wxpython==4.2.2
+          conda install --solver=classic wxpython=4.2.2
           pip install diffpy.pdffit2==1.5.0rc1
           python -m pip install . --no-deps