Fix empty data frame concatenation in emdat_impact_yearlysum

[emanuel-schmid]

impact_data.emdat_impact_yearlysum used to concatenate empty data frames, starting with an empty one and then iteratively adding non-empty ones. This triggers a deprecation warning in pandas >= 2.1.

Changes proposed in this PR:

• Instead of starting with an empty DataFrame, all non-empty DatatFrames are gathered in a generator which is then concatenated at once.

This PR fixes #

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[peanutfun]

@emanuel-schmid I updated the code not to use localization in the empty dataframe but to instead use DataFrame.from_records to avoid having an empty data frame at any point in time. Also, the iteration now only runs over the variable data, and not over the "static" data which can just be added in the end. The tests still run through. Please re-review and merge at your convenience 😇

[emanuel-schmid]

🤩 neat!