Bump to 2.4.0a2

This commit bumps the package version to 2.4.0a2 in preparation for the
2.4.0a2 release.

Signed-off-by: Stephanos Ioannidis <[email protected]>

Author: stephanosio

setup.py

@@ -60,7 +60,7 @@
 
 setup(
     name='windows-curses',
-    version='2.3.3',
+    version='2.4.0a2',
     description="Support for the standard curses module on Windows",
     long_description=LONG_DESCRIPTION,
     long_description_content_type="text/markdown",