`pipx ensurepath` in fish shell results in repeated appending of it to path.

[adikpb]

Describe the bug

pipx ensurepath in fish shell results in repeated appending of it to path. This results in path that just keeps getting longer.

How to reproduce

Running pipx --verbose ensurepath

Success! Added /Users/<redacted>/.local/bin to the PATH environment variable.

Consider adding shell completions for pipx. Run 'pipx completions' for instructions.

You will need to open a new terminal or re-login for the PATH changes to take effect. Alternatively, you can source your shell's config file with e.g. 'source ~/.bashrc'.

Otherwise pipx is ready to go! ✨ 🌟 ✨

Expected behavior Only append to path once using fish_add_path if possible