chore: Mark wheel as Python 3–only

Author: lukaszsocha2

setup.cfg

@@ -1,8 +1,6 @@
 [bdist_wheel]
-# This flag says that the code is written to work on both Python 2 and Python
-# 3. If at all possible, it is good practice to do this. If you cannot, you
-# will need to generate wheels for each Python version that you support.
-universal=1
+# Indicates this library is Python 3–only; Python 2 is not supported
+universal=0
 
 [metadata]
 license_file=LICENSE