docs(misc): fix cover image for testing post (#30395)

<!-- Please make sure you have read the submission guidelines before
posting an PR -->
<!--
https://github.com/nrwl/nx/blob/master/CONTRIBUTING.md#-submitting-a-pr
-->

<!-- Please make sure that your commit message follows our format -->
<!-- Example: `fix(nx): must begin with lowercase` -->

<!-- If this is a particularly complex change or feature addition, you
can request a dedicated Nx release for this pull request branch. Mention
someone from the Nx team or the `@nrwl/nx-pipelines-reviewers` and they
will confirm if the PR warrants its own release for testing purposes,
and generate it for you if appropriate. -->

## Current Behavior
<!-- This is the behavior we have today -->

## Expected Behavior
<!-- This is the behavior we should expect with the changes in this PR
-->

## Related Issue(s)
<!-- Please link the issue being fixed so it gets closed when this is
merged. -->

Fixes #

Author: mhartington

docs/blog/2025-03-17-modern-angular-testing-with-nx.md

@@ -3,7 +3,7 @@ title: 'Modern Angular Testing with Nx'
 slug: modern-angular-testing-with-nx
 authors: ['Jack Hsu']
 tags: ['angular', 'nx']
-cover_image: /blog/images/2025-03-17/modern-angular-testing.avif
+cover_image: /blog/images/2025-03-17/modern-angular-testing.png
 description: 'Learn how Nx enhances Angular testing by integrating modern tools like Playwright and Vitest, improving test speed, reliability, and CI scalability.'
 ---