Require importlib-metadata; python<3.8

Update stdeb.cfg

Author: MatthijsBurgh

setup.cfg

@@ -18,6 +18,7 @@ python_requires = >=3.6
 install_requires =
   colcon-core >= 0.10.0
   colcon-library-path
+  importlib-metadata; python_version < "3.8"
   meson >= 0.60.0
 packages = find:
 

stdeb.cfg

@@ -1,6 +1,6 @@
 [colcon-meson]
 No-Python2:
-Depends3: python3-colcon-core (>= 0.10.0), python3-colcon-library-path, meson (>= 0.60.0)
+Depends3: python3-colcon-core (>= 0.10.0), python3-colcon-library-path, python3 (>= 3.8) | python3-importlib-metadata, meson (>= 0.60.0)
 Suite: jammy noble bookworm trixie
 X-Python3-Version: >= 3.6
 Upstream-Version-Suffix: +upstream