setup.py: Update name for pyicon to have a free valid name for pypi.

setup.py

@@ -11,7 +11,7 @@ with open("requirements.txt") as f:
     install_requires = f.read().strip().split("\n")
 
 setup(
-     name='pyicon',
+     name='pyicon-diagnostics',
      version=version,
      description='Diagnostic python software package for ICON',
      long_description=long_description,