PDEP6 implementation pt 2: eablock.setitem, eablock.putmask
following on from #50626 
This pull request is stale because it has been open for thirty days with no activity. Please [update](https://pandas.pydata.org/pandas-docs/stable/development/contributing.html#updating-your-pull-request) and respond to this comment if you're still interested in working on this. Thanks @MarcoGorelli  @MarcoGorelli do you have time/appetite to start enforcing the PDEP6 deprecation?

If not, is enforcing the deprecation as easy as switching the warnings to exceptions or is there more cleanup? thanks for the ping! yup, I'll get to it - exciting to see it enforced! > @MarcoGorelli do you have time/appetite to start enforcing the PDEP6 deprecation?

doing it today - sorry for the delay, been too caught up with other work projects, but some of them are winding down now