Bump Incident Collaboration plugin to v1.6.0 (#17143)

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

model/feature_flags.go

@@ -31,7 +31,7 @@ func (f *FeatureFlags) SetDefaults() {
 	f.CloudDelinquentEmailJobsEnabled = false
 	f.CollapsedThreads = false
 	f.FilesSearch = false
-	f.PluginIncidentManagement = "1.5.2"
+	f.PluginIncidentManagement = "1.6.0"
 }
 
 func (f *FeatureFlags) Plugins() map[string]string {