update whatsnew for release

Author: wholmgren

docs/sphinx/source/whatsnew/v0.4.3.txt

@@ -1,6 +1,6 @@
 .. _whatsnew_0430:
 
-v0.4.3 (December xx, 2016)
+v0.4.3 (December 28, 2016)
 --------------------------
 
 Enhancements
@@ -11,6 +11,14 @@ Enhancements
 * Added clearsky.detect_clearsky function to determine the clear times
   in a GHI time series. (:issue:`284`)
 
+
+Other
+~~~~~
+
+* Adds Python 3.6 to compatibility statement and pypi classifiers.
+  (:issue:`286`)
+
+
 Contributors
 ~~~~~~~~~~~~