Bump struts2-core in /struts-sandbox/mailreader-course/struts2/migrating

Bumps [struts2-core](https://github.com/apache/struts) from 2.0.0 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>
1 file changed