Bump to (final) release candidate

Bump rc version to 3 for a final check before full release.

Author: st-bender

src/spaceweather/__init__.py

@@ -8,7 +8,7 @@
 """Python interface for space weather indices
 
 """
-__version__ = "0.4.0.rc2"
+__version__ = "0.4.0.rc3"
 
 from .celestrak import *
 from .gfz import *