Avoid Impact storing a pyproj.CRS object

[peanutfun]

Changes proposed in this PR:

• Transform pyproj.CRS into WKT string in Impact.__init__. WKT is the most precise form of storing CRS information, apart from an actual CRS object. This should work fine as the Impact.crs attribute can now safely be stored as string, and inserting the WKT into the Exposures constructor is supported.
• Fix a subtle bug in an impact test

This PR fixes #706

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[peanutfun]

@ChrisFairless could you check if this resolves your issue? Instead of storing CRS objects, I resorted to converting them into WKT strings when passing them to the Impact constructor

[ChrisFairless]

Yes this looks good! Thanks for the fix.

I like how the WKT is recognised by rasterio.crs.CRS.from_user_input so we can still use this to check CRS equality.

[emanuel-schmid]

Agreed. In my experience, WKT is the one that gives the least amount of warnings. 😁
I've added the crs to the attributes list so it's clear that it is a string.

• but then ... maybe it's not. What if it's a rasterio.crs.CRS?

[peanutfun]

rasterio.crs.CRS supports to_wkt, too: https://rasterio.readthedocs.io/en/latest/api/rasterio.crs.html#rasterio.crs.CRS.to_wkt

I'll patch that.

[peanutfun]

@emanuel-schmid Fixed handling of rasterio.crs.CRS here: a5ab8bd

[emanuel-schmid]

Many thanks! To me it's fine for merging, I've added a changlog entry. Feel free to edit.

[peanutfun]

@emanuel-schmid How should we handle the erroneous pylint issue here: https://github.com/CLIMADA-project/climada_python/pull/713/files#diff-1c276908f04d1a0ca5b1692295a586ce54b0937673711203582d3d72099ecdd0R45 ?

[emanuel-schmid]

🤷 I's just suppress it for this particular line by adding # pylint: disable=no-name-in-module at the end.
There are only 2 of this kind throughout climada_python so changing .pylintrc seems over-reacting.