Update changelog for 0.15.0 release

Author: Conengmo

CHANGES.txt

@@ -3,6 +3,7 @@
 
 Breaking changes
 
+- Drop support for Python 3.5 and 3.6 (@ocefpaf #1729)
 - Remove deprecated Stamen tiles (@ocefpaf #1811)
 - Remove `_env` instance attributes (@Conengmo #1817)
 - Use write_png from Branca, remove from Folium (@Conengmo #1708)
@@ -16,6 +17,7 @@ New features
 
 Improvements
 
+- Update jquery to v3.7.1 (@BastienGauthier #1824)
 - Update leaflet.fullscreen plugin to 3.0.0 (@afontenot #1818)
 - Allow Choropleth key_on to traverse through array (@amrutharajashekar #1772)
 - Support TagFilterButton in PolyLine, AntPath and GeoJson (@jamiechoi1995 #1756)