Update maven-invoker-plugin to 3.2.2 to fix JDK16 build

[famod]

Fixes these problems in the JDK16 build:

[INFO] run post-build script verify.bsh
[INFO]   The post-build script did not succeed. Sourced file: inline evaluation of: ``import java.io.*; import java.util.regex.*;  try {     File file = new File( bas . . . '' unknown error: Unable to make public java.lang.AbstractStringBuilder java.lang.AbstractStringBuilder.append(java.lang.String) accessible: module java.base does not "opens java.lang" to unnamed module @430c04a6
[INFO]           it-update-child-modules-002/pom.xml .............. FAILED (6.3 s)

This should be merged ASAP since all more or less recent PRs are affected by this problem (and master of course). /cc @sparsick @mfriedenhagen

I guess sooner or later dependabot would have created a PR for this update, but given the importance I thought better do it now.

[sparsick]

@famod I have no permission to merge your PR. But maybe @khmarbaise can help here. BTW, it is a good idea 👍

[mfriedenhagen]

Thanks, @famod