Revert "[maven-release-plugin] prepare for next development iteration"

This reverts commit 6a7247541bdbbccef8ca9a66f98785d2e83c673c.
Revert "[maven-release-plugin] prepare release 0.9.6.0-BETA"

This reverts commit a52bc9f415657fc11ec106da5860bf9a4bbbbfcb.