Fixed importing concurrent (#249)

Author: jamesramsden-bh

LadybugTools_Engine/Python/src/ladybugtools_toolkit/solar.py

@@ -5,7 +5,7 @@
 import textwrap
 from datetime import datetime
 import json
-import concurrent
+import concurrent.futures
 from dataclasses import dataclass, field
 from enum import Enum, auto
 from pathlib import Path