Use 4.0.6-SNAPSHOT for latest fixes/enhancements

[laeubi]

See

• [tycho-4.0.x] Sort input sources by name eclipse-tycho/tycho#3430
• [tycho-4.0.x] Support access rules defined from the classpath eclipse-tycho/tycho#3447
• [tycho-4.0.x] Move code from mojo to generator and generate missing p2 data if needed eclipse-tycho/tycho#3451
• [tycho-4.0.x] Resolve API baseline with all matching environments eclipse-tycho/tycho#3459
• [tycho-4.0.x] Prepare Tycho for upcomming p2 source requirements changes eclipse-tycho/tycho#3460

[laeubi]

Searching for 'baseline and build artifacts have same version but different contents' shows some bundles that would need to be touched when this is applied.