Bump wildfly-elytron from 1.15.3.Final to 1.15.15.Final

Bumps [wildfly-elytron](https://github.com/wildfly-security/wildfly-elytron) from 1.15.3.Final to 1.15.15.Final.
- [Release notes](https://github.com/wildfly-security/wildfly-elytron/releases)
- [Commits](wildfly-security/wildfly-elytron@1.15.3.Final...1.15.15.Final)

---
updated-dependencies:
- dependency-name: org.wildfly.security:wildfly-elytron
  dependency-type: direct:production
...

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

pom.xml

@@ -103,7 +103,7 @@
         <sun.activation.version>1.2.2</sun.activation.version>
         <org.glassfish.jaxb.xsom.version>2.3.3-b02</org.glassfish.jaxb.xsom.version>
         <undertow.version>2.2.5.Final</undertow.version>
-        <elytron.version>1.15.3.Final</elytron.version>
+        <elytron.version>1.15.15.Final</elytron.version>
         <elytron.undertow-server.version>1.9.0.Final</elytron.undertow-server.version>
         <jetty92.version>9.2.4.v20141103</jetty92.version>
         <jetty93.version>9.3.29.v20201019</jetty93.version>