Issue #5901 Update to javax.servlet.api 4.0.6.

This brings in a change to the javax.servlet.api module-info
to open the javax.servlet.resources package to all modules,
so that the dtds and xsds can be retrieved as resources, either
from the context Classloader.getResource, or
from the ServletContext.class.getResource.

Signed-off-by: Jan Bartel <janb@webtide.com>

pom.xml

@@ -23,7 +23,7 @@
     <log4j2.version>2.13.0</log4j2.version>
     <logback.version>1.3.0-alpha5</logback.version>
     <jetty-test-policy.version>1.2</jetty-test-policy.version>
-    <servlet.api.version>4.0.5</servlet.api.version>
+    <servlet.api.version>4.0.6</servlet.api.version>
     <websocket.api.version>1.1.2</websocket.api.version>
     <jsp.version>9.0.29</jsp.version>
     <infinispan.version>9.4.8.Final</infinispan.version>