Exception with Literal[""]

[Dreamsorcerer]

An exception is thrown if running flake8 and it finds an empty string in a Literal definition.

To Reproduce
I wrote the test for it, so see that:
#11

Output:

Traceback (most recent call last):
  File "/home/ubuntu/.local/bin/flake8", line 8, in <module>
    sys.exit(main())
  File "/home/ubuntu/.local/lib/python3.8/site-packages/flake8/main/cli.py", line 22, in main
    app.run(argv)
  File "/home/ubuntu/.local/lib/python3.8/site-packages/flake8/main/application.py", line 360, in run
    self._run(argv)
  File "/home/ubuntu/.local/lib/python3.8/site-packages/flake8/main/application.py", line 348, in _run
    self.run_checks()
  File "/home/ubuntu/.local/lib/python3.8/site-packages/flake8/main/application.py", line 262, in run_checks
    self.file_checker_manager.run()
  File "/home/ubuntu/.local/lib/python3.8/site-packages/flake8/checker.py", line 334, in run
    self.run_serial()
  File "/home/ubuntu/.local/lib/python3.8/site-packages/flake8/checker.py", line 318, in run_serial
    checker.run_checks()
  File "/home/ubuntu/.local/lib/python3.8/site-packages/flake8/checker.py", line 598, in run_checks
    self.run_ast_checks()
  File "/home/ubuntu/.local/lib/python3.8/site-packages/flake8/checker.py", line 505, in run_ast_checks
    for (line_number, offset, text, _) in runner:
  File "/home/ubuntu/.local/lib/python3.8/site-packages/flake8_annotations_complexity/checker.py", line 23, in run
    too_difficult_annotations = validate_annotations_in_ast_node(
  File "/home/ubuntu/.local/lib/python3.8/site-packages/flake8_annotations_complexity/ast_helpres.py", line 31, in validate_annotations_in_ast_node
    complexity = get_annotation_complexity(annotation)
  File "/home/ubuntu/.local/lib/python3.8/site-packages/flake8_annotations_complexity/ast_helpres.py", line 12, in get_annotation_complexity
    return 1 + get_annotation_complexity(annotation_node.slice.value)  # type: ignore
  File "/home/ubuntu/.local/lib/python3.8/site-packages/flake8_annotations_complexity/ast_helpres.py", line 8, in get_annotation_complexity
    annotation_node = ast.parse(annotation_node.s).body[0].value  # type: ignore
IndexError: list index out of range

[Melevir]

Thanks for the report and for pr with test, it made my work much easier.

Fixed in version 0.0.5 of the plugin.