fix(ObjectPage - TypeScript): fix accessibilityAttributes expandButton.expanded type (#7891)

Doesn’t throw an error when built here, but if ui5wcr is consumed with
`skipLibCheck: false`, it throws:

```sh
 error TS2339: Property 'expanded' does not exist on type 'ButtonAccessibilityAttributes | undefined'.

104                 expanded?: ButtonPropTypes['accessibilityAttributes']['expanded'] | undefined;
                                                                          ~~~~~~~~~~


Found 1 error in node_modules/@ui5/webcomponents-react/dist/components/ObjectPage/types/index.d.ts:104

```

Author: Lukas742

packages/main/src/components/ObjectPage/types/index.ts

@@ -110,7 +110,7 @@ export interface ObjectPagePropTypes extends Omit<CommonProps, 'placeholder'> {
     //todo: rename in next major version to better reflect what part of the ObjectPage it describes
     objectPageAnchorBar?: {
       expandButton?: {
-        expanded?: ButtonPropTypes['accessibilityAttributes']['expanded'] | undefined;
+        expanded?: NonNullable<ButtonPropTypes['accessibilityAttributes']>['expanded'] | undefined;
         accessibleName?: ButtonPropTypes['accessibleName'];
       };
       role?: string;