Dropped Python 3.7 support

Author: wolph

setup.py

@@ -16,7 +16,7 @@
 
 if __name__ == '__main__':
     setuptools.setup(
-        python_requires='>3.6.0',
+        python_requires='>3.8.0',
         name='python-utils',
         version=about['__version__'],
         author=about['__author__'],