⬆️ Update pytz to version 2019.3 (#2101)

Because is one of the dependencies of `pandas` recipe,
and despite that the old version seems to work fine,
I think it's better to go for to the latest available version.

Author: opacam

pythonforandroid/recipes/pytz/__init__.py

@@ -3,8 +3,8 @@
 
 class PytzRecipe(PythonRecipe):
     name = 'pytz'
-    version = '2015.7'
-    url = 'https://pypi.python.org/packages/source/p/pytz/pytz-{version}.tar.bz2'
+    version = '2019.3'
+    url = 'https://pypi.python.org/packages/source/p/pytz/pytz-{version}.tar.gz'
 
     depends = []