Improved support for intervals in postgres

Fixes #393

internal/jet/column_assigment.go

@@ -11,6 +11,13 @@ type columnAssigmentImpl struct {
 	expression Expression
 }
 
+func NewColumnAssignment(serializer ColumnSerializer, expression Expression) ColumnAssigment {
+	return &columnAssigmentImpl{
+		column:     serializer,
+		expression: expression,
+	}
+}
+
 func (a columnAssigmentImpl) isColumnAssigment() {}
 
 func (a columnAssigmentImpl) serialize(statement StatementType, out *SQLBuilder, options ...SerializeOption) {

internal/testutils/test_utils.go

@@ -9,6 +9,7 @@ import (
 	"github.com/go-jet/jet/v2/internal/jet"
 	"github.com/go-jet/jet/v2/internal/utils/throw"
 	"github.com/go-jet/jet/v2/qrm"
+	"github.com/google/go-cmp/cmp"
 	"github.com/google/uuid"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -17,8 +18,6 @@ import (
 	"runtime"
 	"testing"
 	"time"
-
-	"github.com/google/go-cmp/cmp"
 )
 
 // UnixTimeComparer will compare time equality while ignoring time zone