fix[flow]: apply new type cast syntax (#36938)

Quick follow-up to https://github.com/react/react/pull/36786, which
wasn't rebased onto version of `main` that already had Flow upgraded.

packages/react-devtools-shared/src/devtools/views/Components/TreeContext.js

@@ -536,7 +536,7 @@ function reduceSearchState(store: Store, state: State, action: Action): State {
           // Jump directly to a specific result (0-based), clamped to range.
           // This lets users skip past large virtualized lists instead of
           // stepping through results one at a time.
-          const targetIndex = (action: ACTION_GO_TO_SEARCH_RESULT).payload;
+          const targetIndex = (action as ACTION_GO_TO_SEARCH_RESULT).payload;
           searchIndex = Math.max(
             0,
             Math.min(targetIndex, numPrevSearchResults - 1),