test fail with xarray 2024.7.0

[avaldebe]

Describe the bug
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• Pyaerocom version: 0.21.0.dev0
• Computing platform: Ubuntu 22.04.4 LTS and CI
• Configuration file (if applicable):
• Error message (if applicable):

        indexer = either_dict_or_kwargs(indexer, indexer_kwargs, "resample")
        if len(indexer) != 1:
>           raise ValueError("Resampling only supported along single dimensions.")
E           ValueError: Resampling only supported along single dimensions.

.tox/py311/lib/python3.11/site-packages/xarray/core/common.py:1056: ValueError 

To Reproduce
Steps to reproduce the behavior:

tox -re py311 -- tests/aeroval/test_aeroval_HIGHLEV.py -vvx

Expected behavior
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Additional context
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[thorbjoernl]

Deprecation of base and loffsetcauses loffset to be picked up as an indexer which is what causes the exception.

pydata/xarray#9233

https://docs.xarray.dev/en/stable/whats-new.html#breaking-changes

Using the origin or offset parameters is recommended as a replacement for using the base parameter and using time offset arithmetic is recommended as a replacement for using the loffset parameter. (PR9233) By Deepak Cherian.

I think the replacements are not supported by the oldest version of xarray which we currently support which means we either need to bump the oldest supported xarray version or have special logic (I vote for the former).