Version Checks (indicate both or one)

• I have confirmed this bug exists on the lastest release of PyPSA.

• I have confirmed this bug exists on the current master branch of PyPSA.

Issue Description

when comparing add_legend_circles and add_legend_semicircles, you can see that the scale of the semi-circles is off exactly by a factor of 2, meaning that the legend size is half as big as intended.

Reproducible Example

No response

Expected Behavior

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Installed Versions