Update gitignore

Author: Anton Gorinenko

.gitignore

@@ -154,7 +154,9 @@ dmypy.json
 # Reference: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839
 
 # User-specific stuff
+.DS_Store
 .idea
+.idea/
 .idea/**/workspace.xml
 .idea/**/tasks.xml
 .idea/**/usage.statistics.xml