Bump struts2-core in /struts2-fileupload-plugin

Bumps [struts2-core](https://github.com/apache/struts) from 2.1.7-SNAPSHOT to 2.5.30.
- [Release notes](https://github.com/apache/struts/releases)
- [Commits](https://github.com/apache/struts/commits)

---
updated-dependencies:
- dependency-name: org.apache.struts:struts2-core
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
diff --git a/struts2-fileupload-plugin/pom.xml b/struts2-fileupload-plugin/pom.xml
index d970886..a6f8490 100644
--- a/struts2-fileupload-plugin/pom.xml
+++ b/struts2-fileupload-plugin/pom.xml
@@ -42,7 +42,7 @@
         <dependency>
             <groupId>org.apache.struts</groupId>
             <artifactId>struts2-core</artifactId>
-            <version>2.1.7-SNAPSHOT</version>
+            <version>2.5.30</version>
         </dependency>
 
         <dependency>