chore: remove React 16.4's obsolete React imports (#28571)

Signed-off-by: hainenber <dotronghai96@gmail.com>

superset-frontend/src/SqlLab/components/App/index.tsx

@@ -16,7 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
-import React from 'react';
+import { PureComponent } from 'react';
 import { connect } from 'react-redux';
 import { Redirect } from 'react-router-dom';
 import Mousetrap from 'mousetrap';
@@ -111,7 +111,7 @@ interface AppState {
   hash: string;
 }
 
-class App extends React.PureComponent<AppProps, AppState> {
+class App extends PureComponent<AppProps, AppState> {
   hasLoggedLocalStorageUsage: boolean;
 
   constructor(props: AppProps) {