Upgrade REST assured dependency to address Java 16 TCK failures

[Channyboy]

With Java 16, the TCKs will encounter issues when using the rest assured library.
e.g.

org.eclipse.microprofile.metrics.test.MpMetricTest:java.lang.ExceptionInInitializerError: null
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:357)
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:297)
at java.base/java.lang.reflect.Method.checkCanSetAccessible(Method.java:199)
at java.base/java.lang.reflect.AccessibleObject.setAccessible(AccessibleObject.java:130)
at org.codehaus.groovy.reflection.CachedClass$3$1.run(CachedClass.java:86)

See : OpenLiberty/open-liberty#16162

This PR upgrades the rest-assured dependency to address these test failures.