Make MyPy happy

Fixes for various type errors throw by mypy.

portal/__init__.py

 # Taken and adapted from the flaskr tutorial. Database logic adapted from Flask SQLAlchemy Documentation
 # (https://flask-sqlalchemy.palletsprojects.com/en/2.x/contexts/). See LICENSE-3RD-PARTY.md for details.
 import secrets
-from typing import Any, Optional
+from typing import Optional
 from pathlib import Path
 
 from flask import Flask
@@ -9,7 +9,7 @@ from flask_sqlalchemy import SQLAlchemy
 
 from .db_config import get_database_uri, get_uri_for_sqlite
 
-db: Any = SQLAlchemy()
+db = SQLAlchemy()
 
 from .model import *