docs: add code coverage to readme automatically (#5)

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## PR Checklist

- [ ] Addresses an existing open issue: fixes #000
- [ ] That issue was marked as [`status: accepting
prs`](https://github.com/investec/home-run/issues?q=is%3Aopen+is%3Aissue+label%3A%22status%3A+accepting+prs%22)
- [ ] Steps in
[CONTRIBUTING.md](https://github.com/investec/home-run/blob/main/.github/CONTRIBUTING.md)
were taken

## Overview

Adding use of `CODECOV_TOKEN`

.github/workflows/ci.yml

@@ -40,7 +40,9 @@ jobs:
       - uses: actions/checkout@v4
       - uses: ./.github/actions/prepare
       - run: pnpm run test --coverage
-      - uses: codecov/codecov-action@v3
+      - uses: codecov/codecov-action@v4
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}
 
   type_check:
     name: Type Check