fix(openapi3conv): reorder imports for goimports-reviser

The CI's goimports-reviser pass requires kin-openapi's own imports
to sit in their own block separated from third-party ones.

Author: reuvenharrison

openapi3conv/openapi3_conv_test.go

@@ -7,10 +7,11 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/getkin/kin-openapi/openapi3"
-	"github.com/getkin/kin-openapi/openapi3conv"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+
+	"github.com/getkin/kin-openapi/openapi3"
+	"github.com/getkin/kin-openapi/openapi3conv"
 )
 
 func loadV30(t *testing.T, raw string) *openapi3.T {