Update .gitignore to exclude all .iml files

.idea/GHSCPartyBuild.iml

@@ -1,8 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<module version="4">
-  <component name="FacetManager">
-    <facet type="Spring" name="Spring">
-      <configuration />
-    </facet>
-  </component>
-</module>