v9.0.0a4

[integration]

*docs

FIX: (#7330) just use pip install DIRAC for DIRAC client install
FIX: (#7330) updated picture for py3 stack

*Interfaces

FIX: (#7328) Improve performance of job delete/kill/reschedule API
FIX: (#7322) Lower log level for printing version in submitJob

*WorkloadManagementSystem

FIX: (#7327) Allow "ANY" in the valid sites list
NEW: (#7318) initial FutureClient for JobStateUpdate
FIX: (#7316) ElasticJobParametersDB: do not configure the IndexPrefix name