[xmlunit/xmlunit] b7a9e8: fix versions for 2.6.3 release

[Stefan B. <no...@gi...>]

  Branch: refs/tags/v2.6.3
  Home:   https://github.com/xmlunit/xmlunit
  Commit: b7a9e84f167c5e1ef3fb72d72dfbaaa24e8366f3
      https://github.com/xmlunit/xmlunit/commit/b7a9e84f167c5e1ef3fb72d72dfbaaa24e8366f3
  Author: Stefan Bodewig <ste...@fr...>
  Date:   2019-06-21 (Fri, 21 Jun 2019)

  Changed paths:
    M RELEASE_NOTES.md
    M pom.xml
    M xmlunit-assertj/pom.xml
    M xmlunit-core/pom.xml
    M xmlunit-legacy/pom.xml
    M xmlunit-matchers/pom.xml
    M xmlunit-placeholders/pom.xml

  Log Message:
  -----------
  fix versions for 2.6.3 release