Increase minimum python version to 3.7 (#417)

Author: bdraco

pyhap/const.py

@@ -4,7 +4,7 @@
 PATCH_VERSION = 0
 __short_version__ = f"{MAJOR_VERSION}.{MINOR_VERSION}"
 __version__ = f"{__short_version__}.{PATCH_VERSION}"
-REQUIRED_PYTHON_VER = (3, 6)
+REQUIRED_PYTHON_VER = (3, 7)
 
 BASE_UUID = "-0000-1000-8000-0026BB765291"