Update maintainers

Author: davidhassell

setup.py

@@ -265,8 +265,8 @@ def compile():
     version=version,
     description="A CF-compliant earth science data analysis library",
     author="David Hassell",
-    maintainer="David Hassell",
-    maintainer_email="david.hassell@ncas.ac.uk",
+    maintainer="David Hassell, Sadie Bartholomew",
+    maintainer_email="david.hassell@ncas.ac.uk, sadie.bartholomew@ncas.ac.uk",
     author_email="david.hassell@ncas.ac.uk",
     url="https://ncas-cms.github.io/cf-python",
     platforms=["Linux", "MacOS"],