make serve is broken about crystal-book HOT 5 CLOSED

frisco@frisco-520-1047c:~/crystal-book$ make serve
.venv/bin/mkdocs serve
Traceback (most recent call last):
  File ".venv/bin/mkdocs", line 5, in <module>
    from mkdocs.__main__ import cli
  File "/home/frisco/crystal-book/.venv/lib/python3.8/site-packages/mkdocs/__main__.py", line 15, in <module>
    from mkdocs import __version__, config, utils
  File "/home/frisco/crystal-book/.venv/lib/python3.8/site-packages/mkdocs/config/__init__.py", line 1, in <module>
    from mkdocs.config.base import Config, load_config
  File "/home/frisco/crystal-book/.venv/lib/python3.8/site-packages/mkdocs/config/base.py", line 25, in <module>
    from mkdocs import exceptions, utils
  File "/home/frisco/crystal-book/.venv/lib/python3.8/site-packages/mkdocs/utils/__init__.py", line 39, in <module>
    from importlib_metadata import EntryPoint, entry_points
ModuleNotFoundError: No module named 'importlib_metadata'
make: *** [Makefile:20: serve] Error 1

frisco@frisco-520-1047c:~/crystal-book$ python3 -m pip install importlib_metadata
Requirement already satisfied: importlib_metadata in /home/frisco/.local/lib/python3.8/site-packages (6.6.0)
Requirement already satisfied: zipp>=0.5 in /home/frisco/.local/lib/python3.8/site-packages (from importlib_metadata) (3.15.0)

frisco@frisco-520-1047c:~/crystal-book$ python3 -m pip install wheel
Requirement already satisfied: wheel in /usr/lib/python3/dist-packages (0.34.2)