CompatHelper: bump compat for Zygote to 0.7, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the Zygote package from 0.6 to 0.6, 0.7.
This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry.
It is your responsibility to make sure that your package tests pass before you merge this pull request.

[lkdvos]

This should be properly tested (as well as benchmarked), since that version of Zygote introduces the usage of @thunks, which were previously simply discarded.
It is expected that there might be some things that were incorrectly thunked or failed to unthunk, so these should be fixed, and it should hopefully be expected that this improves performance, and not hurts it.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Files with missing lines	Coverage Δ
src/environments/ctmrg_environments.jl	63.15% <100.00%> (+0.39%)	⬆️
src/states/infinitepeps.jl	70.00% <100.00%> (+0.61%)	⬆️
src/utility/svd.jl	85.91% <100.00%> (+0.20%)	⬆️
src/utility/util.jl	52.63% <100.00%> (+0.50%)	⬆️

[pbrehmer]

This would be good to go for me once all test pass (seems to be the case locally). After that we could tag a new release :-)