Grip Broken on Lunar: flask version mismatch

[Brett Holman]

Attempt to use grip fails on ubuntu/lunar with python exception.

$ grip VersionStrings.md
Traceback (most recent call last):
  File "/usr/bin/grip", line 9, in <module>
    load_entry_point('grip==4.2.0', 'console_scripts', 'grip')()
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 522, in load_entry_point
    return get_distribution(dist).load_entry_point(group, name)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 2855, in load_entry_point
    return ep.load()
           ^^^^^^^^^
  File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 2468, in load
    return self.resolve()
           ^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 2474, in resolve
    module = __import__(self.module_name, fromlist=['__name__'], level=0)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/share/grip/grip/__init__.py", line 13, in <module>
    from .api import (
  File "/usr/share/grip/grip/api.py", line 8, in <module>
    from .app import Grip
  File "/usr/share/grip/grip/app.py", line 28, in <module>
    from .assets import GitHubAssetManager, ReadmeAssetManager
  File "/usr/share/grip/grip/assets.py", line 16, in <module>
    from flask import safe_join
ImportError: cannot import name 'safe_join' from 'flask' (/usr/lib/python3/dist-packages/flask/__init__.py)

Version:

$ apt-cache policy grip
grip:
  Installed: 4.2.0-3
  Candidate: 4.2.0-3
  Version table:
 *** 4.2.0-3 100
        100 /var/lib/dpkg/status

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.