Task caching only works if the directory is a subdirectory of cwd

[Hofer-Julian]

Checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pixi, using pixi --version.

Reproducible example

git clone https://github.com/Hofer-Julian/pixi-task-cache-cwd
cd pixi-task-cache-cwd
pixi run start # it is not cached
pixi run start # it is cached but shouldn't be since output folder has been modified

Issue description

Another issue popped up with @Jingru923's work.
My minimal example has a task defined like this

[tasks]
start = { cmd = "echo Hello >> ../folder_a/a.txt", 
          cwd = "folder_b", inputs = ["b.py"],
          outputs = ["../folder_a/a.txt"]}

The cache should be invalidated every single time.
However, when running pixi run --verbose start, one can read from the logs that a.txt isn't tracked.
So we get a cache hit, after the first run.

Related to #1139

Expected behavior

It should be possible to track folders that aren't in cwd.
@wolfv wondered in #1139 (comment)

Now, I am not sure what we should do ... use the cwd or not? I do think that we may not want to use the cwd for the inputs and outputs path computation.

My first instinct was to not take it into account, so I have a slight preference for that.

[wolfv]

We have some larger updates to the cache behavior in main: #1204

I am not sure if it will fix this issue, but it does fix some issues around cwd + cache (uses the project root instead of the task.cwd).

[wolfv]

Could you retry with yesterday's release? I think this is fixed :)

[Hofer-Julian]

I can confirm that now that the project root is used for inputs and outputs this isn't a problem anymore.

[wolfv]

Thanks @Hofer-Julian!