Update version to 2.3.1

Author: Ge0rg3

setup.py

@@ -11,7 +11,7 @@
 
 setup(
     name='Flask-Parameter-Validation',
-    version='2.3.0',
+    version='2.3.1',
     url='https://github.com/Ge0rg3/flask-parameter-validation',
     license='MIT',
     author='George Omnet',