Update astropy timeline

To reflect the roadmap here: https://github.com/astropy/astropy-APEs/blob/master/APE10.rst

Author: bsipocz

site.js

@@ -159,11 +159,10 @@ $(document).ready(function (){
       {content: '1.2', start: '2016-06-23', end: '2016-12-16', py2:true},
       {content: '1.3', start: '2016-12-16', end: '2017-06-01', py2:true},
       {content: '2.0 LTS', start: '2017-06-01', end: '2019-12-31', py2:true},
-      {content: '3.0', start: '2017-12-01', end: '2018-06-01'},
-      {content: '3.1', start: '2018-06-01', end: '2018-12-01'},
-      {content: '3.2', start: '2018-12-01', end: '2019-06-01'},
-      {content: '3.3', start: '2019-06-01', end: '2019-12-01'},
-      {content: '4.0 LTS', start: '2019-12-01', end: '2021-12-01'},
+      {content: '3.0', start: '2018-02-19', end: '2018-11-30'},
+      {content: '3.1', start: '2018-11-30', end: '2019-05-01'},
+      {content: '3.2', start: '2019-05-01', end: '2019-06-01'},
+      {content: '4.0 LTS', start: '2019-11-30', end: '2021-12-01'},
     ],
     'osBrain':[
       {content: '0.x', start: '2016-07-01', end: '2021-12-16'},