nx-builder perform should use SNAPSHOT version in the release branch

nx-builder perform should use SNAPSHOT version in the released branch.

for instance when releasing 5.1.7:

• the 5.1.7 branch should be tagged release-5.1.7) with pom version 5.1.7 (already done)
• the 5.1.7 branch version must be updated to 5.1.7-SNAPSHOT to enable maintenance (to be done)

Note that this will add an extra commit.