Add activate-environment option

[borchero]

Fixes #103.

If updating documentation:

• Updated documentation in https://github.com/prefix-dev/pixi/blob/main/docs/advanced/github_actions.md as well docs: Add environment activation to github actions docs pixi#1371

[pavelzw]

The no-lockfile and auth-Token-install failing tests are unrelated to this pr.

[pavelzw]

Thanks for the effort! Some comments

[pavelzw]

Also, can you bump the version number to 0.7.0?

[pavelzw]

prefix-dev/pixi#1370

[pavelzw]

I would prefer not adding -e default when it's also not being used in pixi install. Maybe we can reuse some logic from the install step.

[pavelzw]

would be nice to remove the json block

is this possible in core.getExecOutput?

[borchero]

is this possible in core.getExecOutput?

Yup, will do

[pavelzw]

@borchero do you want to create a PR updating https://github.com/prefix-dev/pixi/blob/main/docs/advanced/github_actions.md or should i do that?

[borchero]

Feel free to go ahead @pavelzw, I'd only get to it tonight 😅

[pavelzw]

prefix-dev/pixi#1371