fix for minimu and maximum in validators, added validator for choices and choices param for BaseField, include tests

tests/test_model_definition.py

@@ -28,6 +28,7 @@ class ExampleModel(Model):
     test_json: fields.JSON(default={})
     test_bigint: fields.BigInteger(default=0)
     test_decimal: fields.Decimal(scale=10, precision=2)
+    test_decimal2: fields.Decimal(max_digits=10, decimal_places=2)
 
 
 fields_to_check = [
@@ -55,7 +56,7 @@ class ExampleModel2(Model):
 @pytest.fixture()
 def example():
     return ExampleModel(
-        pk=1, test_string="test", test_bool=True, test_decimal=decimal.Decimal(3.5)
+        pk=1, test_string="test", test_bool=True, test_decimal=decimal.Decimal(3.5), test_decimal2=decimal.Decimal(5.5)
     )
 
 
@@ -73,6 +74,8 @@ def test_model_attribute_access(example):
     assert example.test_float is None
     assert example.test_bigint == 0
     assert example.test_json == {}
+    assert example.test_decimal == 3.5
+    assert example.test_decimal2 == 5.5
 
     example.test = 12
     assert example.test == 12