Add line to geolegend (#783)

Author: gepcel

ultraplot/legend.py

@@ -192,6 +192,7 @@ def create_artists(self, legend, orig_handle, *args, **kwargs):
     "rectangle": mpath.Path(
         [[0, 0], [2, 0], [2, 1], [0, 1], [0, 0]], closed=True, readonly=True
     ),
+    "line": mpath.Path([[0,0], [1,0]], readonly=True),
 }
 _GEOMETRY_SHAPE_ALIASES = {
     "box": "square",