pipx doesn't remove injected apps' symlinks after main package is uninstalled

[vanyakosmos]

Describe the bug

pipx doesn't remove injected apps' symlinks after main package is uninstalled

How to reproduce

# install
pipx install black
pipx inject --include-apps black flake8
pipx list
# here you will see black, blackd, flake8 under black package

# remove
pipx uninstall black
pipx list
# no black package and injected ones

# install again
pipx install black
pipx list
# here you will see black, blackd, flake8 under black package
# flake8 alias was not removed, but flake8 itself is not installed
# and it is displayed in the list for some reasons

Expected behavior

Aliases of injected app should be removed after main package was deleted.

[itsayellow]

Duplicate of #221