Also support python<3.8

Author: MatthijsBurgh

colcon_meson/build.py

@@ -2,7 +2,6 @@
 # Licensed under the Apache License, Version 2.0
 
 from argparse import ArgumentParser, Namespace
-from importlib.metadata import version
 import json
 import os
 from pathlib import Path
@@ -19,6 +18,12 @@
 from mesonbuild.build import OptionKey
 from mesonbuild.mesonmain import CommandLineParser
 
+
+if sys.version_info >= (3, 8):
+    from importlib.metadata import version
+else:
+    from importlib_metadata import version
+
 if tuple(map(int, version("meson").split(".")[:3])) >= (1, 10, 0):
     from mesonbuild import cmdline as meson_cmd
 else: