chore(angular): update typescript to support Angular 20 (#30516)

Issue number: N/A

---------

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## What is the current behavior?
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Angular 20 test app is using an unsupported Typescript version.

## What is the new behavior?
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this PR. -->

Angular 20 only supports Typescript 5.8+. I forgot to update it in an
earlier [PR](https://github.com/ionic-team/ionic-framework/pull/30507).

- Upgraded TS to the proper version.

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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## Other information

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N/A

packages/angular/test/apps/ng20/package.json

@@ -60,7 +60,7 @@
     "eslint": "^8.57.0",
     "ts-loader": "^6.2.2",
     "ts-node": "^8.3.0",
-    "typescript": "^5.6.3",
+    "typescript": "^5.8.0",
     "wait-on": "^8.0.1",
     "webpack": "^5.61.0",
     "webpack-cli": "^4.9.2"