App extension: Bug Fix - send the keys file does not work correctly

The attached file is not detected as keys files when the user selects it in the room history.
The associated mimetype was wrong

RiotShareExtension/Model/ShareExtensionManager.m

@@ -450,7 +450,11 @@ typedef NS_ENUM(NSInteger, ImageCompressionMode)
         }
         return;
     }
-    NSString *mimeType = [fileUrl pathExtension];
+    
+    NSString *mimeType;
+    CFStringRef uti = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, (__bridge CFStringRef)[fileUrl pathExtension] , NULL);
+    mimeType = (__bridge_transfer NSString *) UTTypeCopyPreferredTagWithClass(uti, kUTTagClassMIMEType);
+    CFRelease(uti);
     
     __weak typeof(self) weakSelf = self;