Move version and author information to separate file. The current location leads to problems with dependencies which are only resolved after running pip.

setup.py

@@ -1,5 +1,5 @@
 from setuptools import setup
-from wavinfo import __author__, __license__, __version__
+from metadata import __author__, __license__, __version__
 
 with open("README.md", "r") as fh:
     long_description = fh.read()