Version pinning flask-sqlalchemy version to 2.5.1 or less (#360)

See related issue: #359

Author: srprash

tox.ini

@@ -83,7 +83,7 @@ deps =
     ext-flask: flask >= 0.10
 
     ext-flask_sqlalchemy: flask >= 0.10
-    ext-flask_sqlalchemy: Flask-SQLAlchemy
+    ext-flask_sqlalchemy: Flask-SQLAlchemy <= 2.5.1
 
     ext-sqlalchemy: sqlalchemy