Fix big grid crashing due to missing React import

by fixing the cause rather than the symptom: this upgrades the code to use the new, recommended JSX transform mode of React 17+, which no longer requires you to import React manually just to write JSX.

src/button/Button.tsx

@@ -13,7 +13,7 @@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */
-import React, { forwardRef, useCallback } from "react";
+import { forwardRef, useCallback } from "react";
 import { PressEvent } from "@react-types/shared";
 import classNames from "classnames";
 import { useButton } from "@react-aria/button";