Replace the diff parser imports with the modified path.

test/test_parser/test_diff_parser.py

@@ -7,7 +7,7 @@ from jedi import debug
 from jedi.common import splitlines
 from jedi import cache
 from jedi.parser.python import load_grammar
-from jedi.parser.diff import DiffParser
+from jedi.parser.python.diff import DiffParser
 from jedi.parser import ParserWithRecovery
 
 

test/test_parser/test_old_fast_parser.py

@@ -11,7 +11,7 @@ from textwrap import dedent
 import jedi
 from jedi._compatibility import u
 from jedi.parser.python import load_grammar
-from jedi.parser.diff import FastParser
+from jedi.parser.python.diff import FastParser
 from jedi.parser.utils import save_parser