Fix linting errors.

Author: CXuesong

test/plugins/test_symbols.py

@@ -106,4 +106,4 @@ def child_sym(sym, name):
     assert len(sym('B')['children']) == 1
     assert child_sym(sym('B'), '__init__')['kind'] == SymbolKind.Function
     assert child_sym(sym('B'), '__init__')['detail'] == 'B.__init__'
-    assert sym('main')['kind'] == SymbolKind.Function
+    assert sym('main')['kind'] == SymbolKind.Function