chore: fix paymaster tests in cicd

[joepegler]

PR-Codex overview

This PR focuses on updating configuration settings in the GitHub Actions workflow, refining the test files for the BicoPaymasterClient, and improving the README documentation for installation and testing instructions.

Detailed summary

• Updated .github/workflows/unit-tests.yml to replace BUNDLER_URL and add PAYMASTER_URL from secrets.
• Simplified smartSessions.decorators.test.ts by removing unnecessary moduleData.
• Removed unused BicoBundlerClient in createBicoPaymasterClient.test.ts.
• Revised README installation steps by removing the dependency installation command and enhancing usage instructions.

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[github-actions]

size-limit report 📦

Path	Size
core (esm)	14.31 KB (0%)
core (cjs)	20.21 KB (0%)
bundler (tree-shaking)	543 B (0%)
paymaster (tree-shaking)	123 B (0%)