fix(anvil) : fix returning type (#6337)

* Update api.rs

* Update api.rs

Author: DoTheBestToGetTheBest

crates/anvil/src/eth/api.rs

@@ -1708,16 +1708,17 @@ impl EthApi {
     pub async fn anvil_metadata(&self) -> Result<AnvilMetadata> {
         node_info!("anvil_metadata");
         let fork_config = self.backend.get_fork();
-
+        let chain_id_uint = U256::from(self.backend.chain_id().low_u64());
+        let latest_block_number_uint = U64::from(self.backend.best_number().low_u64());
         Ok(AnvilMetadata {
             client_version: CLIENT_VERSION,
-            chain_id: self.backend.chain_id(),
+            chain_id: chain_id_uint,
             latest_block_hash: self.backend.best_hash(),
-            latest_block_number: self.backend.best_number(),
+            latest_block_number: latest_block_number_uint,
             instance_id: *self.instance_id.read(),
             forked_network: fork_config.map(|cfg| ForkedNetwork {
-                chain_id: cfg.chain_id().into(),
-                fork_block_number: cfg.block_number().into(),
+                chain_id: U256::from(cfg.chain_id()),
+                fork_block_number: U64::from(cfg.block_number()),
                 fork_block_hash: cfg.block_hash(),
             }),
         })