Update kin-openapi to 0.13

Pulled in the latest kin-openapi and fixed a test error, since
descriptions on responses are required in the spec.

Author: mromaszewicz

oapi_validate_test.go

@@ -27,6 +27,7 @@ import (
 	"github.com/labstack/echo/v4"
 	echomiddleware "github.com/labstack/echo/v4/middleware"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 var testSchema = `openapi: "3.0.0"
@@ -48,6 +49,7 @@ paths:
             maximum: 100
       responses:
         '200':
+            description: success
             content:
               application/json:
                 schema:
@@ -116,7 +118,7 @@ func doPost(t *testing.T, e *echo.Echo, url string, jsonBody interface{}) *httpt
 
 func TestOapiRequestValidator(t *testing.T) {
 	swagger, err := openapi3.NewSwaggerLoader().LoadSwaggerFromData([]byte(testSchema))
-	assert.NoError(t, err, "Error initializing swagger")
+	require.NoError(t, err, "Error initializing swagger")
 
 	// Create a new echo router
 	e := echo.New()