Update master to 9.0 (#3055)

shared/versions/stack/master.asciidoc

@@ -1,18 +1,18 @@
-:version:                8.16.0
+:version:                9.0.0-beta1
 ////
 bare_version never includes -alpha or -beta
 ////
-:bare_version:           8.16.0
-:logstash_version:       8.16.0
-:elasticsearch_version:  8.16.0
-:kibana_version:         8.16.0
-:apm_server_version:     8.16.0
+:bare_version:           9.0.0
+:logstash_version:       9.0.0
+:elasticsearch_version:  9.0.0
+:kibana_version:         9.0.0
+:apm_server_version:     9.0.0
 :branch:                 master
-:minor-version:          8.16
-:major-version:          8.x
-:prev-major-version:     7.x
-:prev-major-last:        7.17
-:major-version-only:     8
+:minor-version:          9.0
+:major-version:          9.x
+:prev-major-version:     8.x
+:prev-major-last:        8.16
+:major-version-only:     9
 :ecs_version:            8.11
 :esf_version:            master
 :ece-version-link:       current