Revert "Turn the chosen username to lowercase"

This reverts commit ea7ba3e969.

matrix_synapse_saml_mozilla/res/script.js

@@ -65,9 +65,7 @@ let submitUsername = function(username) {
     return;
   }
 
-    // Since we're trying to register the username converted to lower case, check the
-    // availability with the right case.
-    let check_uri = 'check?' + buildQueryString({"username": username.toLowerCase()});
+    let check_uri = 'check?' + buildQueryString({"username": username});
     fetch(check_uri, {
         "credentials": "include",
     }).then((response) => {

matrix_synapse_saml_mozilla/username_picker.py

@@ -155,8 +155,6 @@ class SubmitResource(AsyncResource):
             _return_html_error(400, "missing username", request)
             return
         localpart = request.args[b"username"][0].decode("utf-8", errors="replace")
-        # Convert the username to lower case.
-        localpart = localpart.lower()
         logger.info("Registering username %s", localpart)
         try:
             registered_user_id = await self._module_api.register_user(