fix：兼容 spring cloud 低版本的 gateway

yudao-gateway/pom.xml

@@ -32,7 +32,12 @@
         <!-- Gateway 网关相关 -->
         <dependency>
             <groupId>org.springframework.cloud</groupId>
-            <artifactId>spring-cloud-starter-gateway-server-webflux</artifactId>
+            <artifactId>spring-cloud-starter-gateway</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>javax.servlet</groupId>
+            <artifactId>javax.servlet-api</artifactId>
         </dependency>
 
         <dependency>

yudao-gateway/src/main/resources/application.yaml

@@ -5,8 +5,7 @@ spring:
   profiles:
     active: local
 
-  http:
-    codecs:
+  codec:
     max-in-memory-size: 10MB # 调整缓冲区大小https://gitee.com/zhijiantianya/yudao-cloud/pulls/176
 
   # Jackson 配置项
@@ -28,8 +27,6 @@ spring:
   cloud:
     # Spring Cloud Gateway 配置项，对应 GatewayProperties 类
     gateway:
-      server:
-        webflux:
       # 路由配置项，对应 RouteDefinition 数组
       routes:
         ## system-server 服务