Free esmpy of >=8.6.0 pin and pin iris-grib >=0.20.0

[valeriupredoi]

Description

Closes #2535

Long story short:

• iris-grib needs be pinned due to Add support for native ERA5 data in GRIB format #2178
• ncl has a hard pin esmf<8.6.0 so whatever ncl gets installed for esmf/esmpy>=8.6.0 is about two years old (still 6.6.2 but a very old build, that did not have the pin in)
• it is rather safe to use esmf/esmpy<8.6.0 ie 8.4.2 as per Is the fix from PR 353 compatible with esmpy<8.6.0 as well? SciTools/iris-esmf-regrid#415

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.90%. Comparing base (5b28372) to head (672b376).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2542   +/-   ##
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  Coverage   94.90%   94.90%           
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  Files         251      251           
  Lines       14295    14295           
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  Hits        13566    13566           
  Misses        729      729           

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[valeriupredoi]

OK @schlunma - you should be fine with an unpinned esmf/esmpy and iris-grib>=0.20.0 - even NCL installs fine (...) but if we want to build a package with any Python <3.12 and NCL then we'd have to pin importlib_metadata <8 as per ESMValGroup/ESMValTool#3700 - we did that for ESMValTool in the last release, so it's no biggie. TL;DR if you happy you can merge this 🍺

[valeriupredoi]

(...) = ncl build h7cb714c_54 which the latest build ☺️

[valeriupredoi]

@schlunma cheers Manu, go ahead and merge at will 🍺

[schlunma]

Great, thanks V!!