dependency: Bump spring-core version to 5.1.18.RELEASE in sentinel-zuul2-adapter pom (#2028)

sentinel-adapter/sentinel-zuul2-adapter/pom.xml

@@ -45,7 +45,7 @@
         <dependency>
             <groupId>org.springframework</groupId>
             <artifactId>spring-core</artifactId>
-            <version>5.1.9.RELEASE</version>
+            <version>5.1.18.RELEASE</version>
         </dependency>
 
         <dependency>
@@ -60,4 +60,4 @@
         </dependency>
     </dependencies>
 
-</project>
+</project>