feat: added LowerCaseString field

creyPY/const/__init__.py

@@ -1,3 +1,4 @@
+from .fields import *  # noqa
 from .groups import *  # noqa
 from .i18n import *  # noqa
 from .stripe import *  # noqa

creyPY/const/fields.py

@@ -0,0 +1,17 @@
+from sqlalchemy import types
+
+
+class LowerCaseString(types.TypeDecorator):
+    """Converts strings to lower case on the way in."""
+
+    impl = types.String
+    cache_ok = True
+
+    def process_bind_param(self, value, dialect):
+        if value is None:
+            return value
+        return value.lower()
+
+    @property
+    def python_type(self):
+        return str