Add missing mypy type

Author: oschwald

.github/workflows/lint.yml

@@ -22,7 +22,7 @@ jobs:
       - name: Install dependencies
         run: |
               python -m pip install --upgrade pip
-              pip install --upgrade pylint black mypy voluptuous-stubs
+              pip install --upgrade pylint black mypy voluptuous-stubs types-maxminddb
 
       - name: Install
         run: python setup.py install