Hopefully it would remove it & its files from being cached in the action. & also
not includde into environment.

For future caching configuraiton.

For 1:1 according cache to it.

Sources are stored separately.

Before this cache was storing per Platform/GHC sources & compiled results
together. While deps sources does not depend on platform or GHC, they are
platform & GHC agnostic. Because sources & compiled results were stored togather
& sources took ~1/2-2/3 of that - cache stored multiple duplicates of the same
source code.

This config stores the source code separately.

And at the same time tries to store & share all source code which may be needed.
& all compiled deps that would be used in different workflows.