fix: exclude tests from build and update node requirement

[jkyberneees]

No description provided.

[Copilot]

Pull Request Overview

This PR addresses two technical issues: excluding test files from the TypeScript build process and updating the minimum Node.js version requirement to accurately reflect the features used by the library.

• Added **/*.test.ts pattern to tsconfig.build.json exclude list to prevent test files in src/ from being included in the build output
• Updated minimum Node.js version from 10.4.0+ to 11.0.0+ to reflect the requirement for global TextEncoder support

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
tsconfig.build.json	Adds **/*.test.ts to exclude pattern to ensure test files in src/ directory are not compiled into the build output
README.md	Updates minimum Node.js version requirement from 10.4.0+ to 11.0.0+ to accurately reflect the need for both BigInt and global TextEncoder support

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