Fix schema typo (#7491)

Author: jmduke

rest_framework/schemas/openapi.py

@@ -50,7 +50,7 @@ def check_duplicate_operation_id(self, paths):
                         'You have a duplicated operationId in your OpenAPI schema: {operation_id}\n'
                         '\tRoute: {route1}, Method: {method1}\n'
                         '\tRoute: {route2}, Method: {method2}\n'
-                        '\tAn operationId has to be unique accros your schema. Your schema may not work in other tools.'
+                        '\tAn operationId has to be unique across your schema. Your schema may not work in other tools.'
                         .format(
                             route1=ids[operation_id]['route'],
                             method1=ids[operation_id]['method'],