Bump io.undertow:undertow-core from 2.3.15.Final to 2.3.18.Final

Bumps [io.undertow:undertow-core](https://github.com/undertow-io/undertow) from 2.3.15.Final to 2.3.18.Final.
- [Release notes](https://github.com/undertow-io/undertow/releases)
- [Commits](undertow-io/undertow@2.3.15.Final...2.3.18.Final)

---
updated-dependencies:
- dependency-name: io.undertow:undertow-core
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

environments/se/pom.xml

@@ -24,7 +24,7 @@
     </description>
 
    <properties>
-      <undertow.version>2.3.15.Final</undertow.version>
+      <undertow.version>2.3.18.Final</undertow.version>
    </properties>
 
    <dependencyManagement>