Fix default `TOKEN_EXCHANGE_RATE_REFETCH_INTERVAL` (#7270)

* Fix default TOKEN_EXCHANGE_RATE_REFETCH_INTERVAL

* Update CHANGELOG.md

---------

Co-authored-by: Victor Baranov <baranov.viktor.27@gmail.com>

CHANGELOG.md

@@ -6,6 +6,8 @@
 
 ### Fixes
 
+- [#7270](https://github.com/blockscout/blockscout/pull/7270) - Fix default `TOKEN_EXCHANGE_RATE_REFETCH_INTERVAL`
+
 ### Chore
 
 <details>

config/runtime.exs

@@ -260,7 +260,7 @@ config :explorer, Explorer.ExchangeRates.Source.CoinGecko,
 config :explorer, Explorer.ExchangeRates.TokenExchangeRates,
   enabled: !ConfigHelper.parse_bool_env_var("DISABLE_TOKEN_EXCHANGE_RATE", "true"),
   interval: ConfigHelper.parse_time_env_var("TOKEN_EXCHANGE_RATE_INTERVAL", "5s"),
-  refetch_interval: ConfigHelper.parse_time_env_var("TOKEN_EXCHANGE_RATE_REFETCH_INTERVAL", nil),
+  refetch_interval: ConfigHelper.parse_time_env_var("TOKEN_EXCHANGE_RATE_REFETCH_INTERVAL", "1h"),
   max_batch_size: ConfigHelper.parse_integer_env_var("TOKEN_EXCHANGE_RATE_MAX_BATCH_SIZE", 150)
 
 config :explorer, Explorer.Market.History.Cataloger, enabled: !disable_indexer?