updated .gitignore

Author: Lukas Reithmeier

.gitignore

@@ -133,6 +133,7 @@ dmypy.json
 # Reference: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839
 
 .idea
+*.iml
 
 # User-specific stuff
 .idea/**/workspace.xml