fix: add missing session field to test context, update snapshot

PlatformExtensionContext gained a session field from #7576.
Add session: None to the test helper. Update snapshot.

Author: tlongwell-block

crates/goose/src/agents/platform_extensions/analyze/mod.rs

@@ -301,6 +301,7 @@ mod tests {
         PlatformExtensionContext {
             extension_manager: None,
             session_manager: Arc::new(SessionManager::new(std::env::temp_dir())),
+            session: None,
         }
     }