Fix error when loading ACP registry (#48957)

Bennet Bo Fenner created

This [change](https://github.com/agentclientprotocol/registry/pull/34)
broke the ACP registry in Zed, since we did not have `#[serde(default)]`
on the `_extensions` field.

- [x] Tests or screenshots needed?
- [x] Code Reviewed
- [x] Manual QA

Release Notes:

- Fixed an issue where the ACP registry would fail to load

Change summary

crates/project/src/agent_registry_store.rs | 2 --
1 file changed, 2 deletions(-)

Detailed changes

crates/project/src/agent_registry_store.rs 🔗

@@ -536,8 +536,6 @@ struct RegistryIndex {
     #[serde(rename = "version")]
     _version: String,
     agents: Vec<RegistryEntry>,
-    #[serde(rename = "extensions")]
-    _extensions: Vec<RegistryEntry>,
 }
 
 #[derive(Deserialize)]