fix: prevent email notifications to removed members

Content will retain an older member in visible_to, even if that member
was removed from the network.

go/cmd/emailnotifierjob/main.go

@@ -247,7 +247,10 @@ func resolveMembers(visibleTo []string, networkMembers map[string]bool) map[stri
 	for _, entry := range visibleTo {
 		if strings.HasPrefix(entry, "human:") {
 			humanId := strings.TrimPrefix(entry, "human:")
-			members[humanId] = true
+			// human can be in visible_to, but no longer a member of the network
+			if _, ok := networkMembers[humanId]; ok {
+				members[humanId] = true
+			}
 		} else if strings.HasPrefix(entry, "network:") {
 			// Expand to all network members
 			for id := range networkMembers {