chore(quickstart): migrate to Jest 30 (#3018)

Install Jest 30 peer dependencies as required by @backstage/cli 0.36.0 and fix test incompatibilities for Jest 30 and JSDOM 27.

Signed-off-by: Jon Koops <jonkoops@gmail.com>

Author: jonkoops

workspaces/quickstart/package.json

@@ -47,7 +47,12 @@
     "@backstage/e2e-test-utils": "^0.1.2",
     "@backstage/repo-tools": "^0.17.0",
     "@changesets/cli": "^2.27.1",
+    "@jest/environment-jsdom-abstract": "^30.3.0",
     "@playwright/test": "1.58.2",
+    "@types/jest": "^30.0.0",
+    "@types/jsdom": "^27.0.0",
+    "jest": "^30.3.0",
+    "jsdom": "^27.1.0",
     "knip": "^5.27.4",
     "node-gyp": "^9.0.0",
     "prettier": "^2.3.2",

workspaces/quickstart/plugins/quickstart/src/components/QuickstartButton/QuickstartButton.test.tsx

@@ -148,6 +148,6 @@ describe('QuickstartButton', () => {
     );
 
     const button = screen.getByTestId('quickstart-button');
-    expect(button).toHaveStyle('background-color: red');
+    expect(button).toHaveStyle('background-color: rgb(255, 0, 0)');
   });
 });