更新spring-boot到2.5.6，spring-cloud到2020.0.4

pom.xml

@@ -17,8 +17,8 @@
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
         <java.version>1.8</java.version>
-        <spring-boot.version>2.5.4</spring-boot.version>
-        <spring-cloud.version>2020.0.3</spring-cloud.version>
+        <spring-boot.version>2.5.6</spring-boot.version>
+        <spring-cloud.version>2020.0.4</spring-cloud.version>
         <spring-cloud-alibaba.version>2021.1</spring-cloud-alibaba.version>
         <alibaba.nacos.version>2.0.3</alibaba.nacos.version>
         <spring-boot-admin.version>2.5.1</spring-boot-admin.version>