Update Flask-WTF to 0.14.3 to fix python2 - python3 transition

When updating I Hate Money from python2 to python3, any leftover cookie
set from python2 causes the python3 version to crash when reading the
cookie back.

This is a bug/omission in Flask-WTF: pallets-eco/flask-wtf#275

It was fixed in 0.14.3 with: pallets-eco/flask-wtf@eff54ec

setup.py

@@ -66,7 +66,7 @@ def parse_requirements(filename):
           "Flask-RESTful==0.3.7",
           "Flask-Script==2.0.6",
           "Flask-SQLAlchemy==2.4.0",
-          "Flask-WTF==0.14.2",
+          "Flask-WTF==0.14.3",
           "itsdangerous==1.1.0",
           "Jinja2==2.10.1",
           "six==1.14.0",