setup: enable setup_tools_scm

As already indicated by use_scm_version, this should be avialable during
setup.

Signed-off-by: Rouven Czerwinski <rouven@czerwinskis.de>

Author: Emantor

setup.py

@@ -11,6 +11,7 @@
     use_scm_version=True,
     url='https://github.com/labgrid-project',
     python_requires='>=3.5, <3.8',
+    setup_requires=['setuptools_scm'],
     install_requires=[
         'labgrid>=0.1.0',
     ],