Update docs/updating-users-passwords.md: triple backticks for syntax highlighting

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

docs/updating-users-passwords.md

@@ -23,7 +23,7 @@ docker exec -it matrix-synapse /usr/local/bin/hash_password -c /data/homeserver.
 
 and then connecting to the postgres server and executing:
 
-```
+```sql
 UPDATE users SET password_hash = '<password-hash>' WHERE name = '@someone:example.com'
 ```