Broker invoice, nonzero for 2025-06 because of resource increase in tpo/anti-censorship/pluggable-transports/snowflake#40465 (comment 3211319).

Snowflake-costs.md

@@ -66,6 +66,7 @@
 |--:|---:|
 |2025-01|€295.71|
 |2025-02|€36.51|
+|2025-06|€8.34|
 
 ## Bridge hosting