Memoize getAgent method

src/state/session/index.tsx

@@ -24,11 +24,14 @@ import {readLabelers} from './agent-config'
 let __globalAgent: BskyAgent = PUBLIC_BSKY_AGENT
 
 export function useAgent() {
-  return {
+  return React.useMemo(
-    getAgent() {
+    () => ({
-      return __globalAgent
+      getAgent() {
-    },
+        return __globalAgent
-  }
+      },
+    }),
+    [],
+  )
 }
 
 export type SessionAccount = persisted.PersistedAccount