test(tab-nav): stabilize test (#8356)

**Related Issue:** N/A

## Summary

Waits for changes after interacting with the tab title to account for
some internal eventing going on.

Author: jcfranco

packages/calcite-components/src/components/tab-nav/tab-nav.e2e.ts

@@ -32,9 +32,11 @@ describe("calcite-tab-nav", () => {
     expect(activeEventSpy).toHaveReceivedEventTimes(0);
 
     await firstTabTitle.click();
+    await page.waitForChanges();
     expect(activeEventSpy).toHaveReceivedEventTimes(1);
 
     await page.keyboard.press("Enter");
+    await page.waitForChanges();
     expect(activeEventSpy).toHaveReceivedEventTimes(2);
   });