move convert_to_sql_value to a different file to prevent circular imports

Author: dantownsend

piccolo/columns/combination.py

@@ -4,7 +4,7 @@
 from piccolo.columns.operators.comparison import ComparisonOperator
 from piccolo.custom_types import Combinable, Iterable
 from piccolo.querystring import QueryString
-from piccolo.query.sql_values import convert_to_sql_value
+from piccolo.utils.sql_values import convert_to_sql_value
 
 if t.TYPE_CHECKING:
     from piccolo.columns.base import Column

piccolo/query/mixins.py

@@ -4,7 +4,7 @@
 
 from piccolo.columns import And, Column, Secret, Where, Or
 from piccolo.custom_types import Combinable
-from piccolo.query.sql_values import convert_to_sql_value
+from piccolo.utils.sql_values import convert_to_sql_value
 from piccolo.querystring import QueryString
 
 if t.TYPE_CHECKING:  # pragma: no cover

piccolo/table.py

@@ -37,7 +37,7 @@
 )
 from piccolo.query.methods.indexes import Indexes
 from piccolo.query.methods.create_index import CreateIndex
-from piccolo.query.sql_values import convert_to_sql_value
+from piccolo.utils.sql_values import convert_to_sql_value
 from piccolo.querystring import QueryString, Unquoted
 from piccolo.utils import _camel_to_snake