Add 'ERA5-Land' dataset to predefined datasets

[MarkMelotto]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.17%. Comparing base (13975dd) to head (9228f12).

Files with missing lines	Patch %	Lines
src/ewatercycle/base/parameter_set.py	0.00%	1 Missing ⚠️
src/ewatercycle/util.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #499   +/-   ##
=======================================
  Coverage   79.17%   79.17%           
=======================================
  Files          28       28           
  Lines        1882     1882           
  Branches      168      168           
=======================================
  Hits         1490     1490           
  Misses        330      330           
  Partials       62       62           

Files with missing lines	Coverage Δ
src/ewatercycle/_forcings/caravan.py	83.01% <100.00%> (ø)
src/ewatercycle/esmvaltool/builder.py	68.96% <ø> (ø)
src/ewatercycle/esmvaltool/datasets.py	100.00% <ø> (ø)
src/ewatercycle/observation/caravan.py	100.00% <100.00%> (ø)
src/ewatercycle/observation/grdc.py	82.22% <ø> (ø)
src/ewatercycle/base/parameter_set.py	62.37% <0.00%> (ø)
src/ewatercycle/util.py	85.38% <0.00%> (ø)

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[MarkMelotto]

@BSchilperoort I dont see why this should not be fine