Merge v2.9.x into main

[schlunma]

Merge v2.9.x into main to get versioning correctly.

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Checklist

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[codecov]

Codecov Report

Merging #2128 (991f969) into main (92e20fd) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #2128   +/-   ##
=======================================
  Coverage   93.08%   93.08%           
=======================================
  Files         237      237           
  Lines       12785    12792    +7     
=======================================
+ Hits        11901    11908    +7     
  Misses        884      884           

Impacted Files	Coverage Δ
esmvalcore/_citation.py	80.99% <100.00%> (ø)
esmvalcore/cmor/_fixes/cmip6/ec_earth3_veg.py	100.00% <100.00%> (ø)
esmvalcore/cmor/_fixes/cmip6/giss_e2_1_g.py	100.00% <100.00%> (ø)
esmvalcore/esgf/_search.py	100.00% <100.00%> (ø)
esmvalcore/preprocessor/_io.py	86.74% <100.00%> (ø)
esmvalcore/preprocessor/_regrid.py	98.25% <100.00%> (-0.03%)	⬇️