Update CI badge in README.md

[sapientpants]

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Other information

[Copilot]

Pull Request Overview

Updates the CI workflow badge in the README to reflect a rename from ci.yml to main.yml workflow file.

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_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[deepsource-io]

Here's the code health analysis summary for commits d900227..209e1f5. View details on DeepSource ↗.

Analysis Summary

Analyzer	Status	Summary	Link
Test coverage	✅ Success		View Check ↗
JavaScript	✅ Success		View Check ↗

Code Coverage Report

Metric	Aggregate	Javascript
Branch Coverage	88.5%	88.5%
Composite Coverage	88.7%	88.7%
Line Coverage	88.7%	88.7%

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