Fix center of outage calculation (#24)

Solves #23

Reviewed-on: #24

geospatial.py

@@ -0,0 +1,11 @@
+from shapely import MultiPolygon, Polygon
+
+
+def convert_outage_geometry(event) -> MultiPolygon:
+    assert event["polygons"]["type"] == "polygon"
+    assert event["polygons"]["hasZ"] is False
+    assert event["polygons"]["hasM"] is False
+    polygon_list = []
+    for ring in event["polygons"]["rings"]:
+        polygon_list.append(Polygon(ring))
+    return MultiPolygon(polygon_list)