chore: version bump

[joepegler]

PR-Codex overview

This PR updates the @biconomy/account package to version 4.2.0, introducing improvements in token balance fetching, signature support, utility helpers, and more.

Detailed summary

• Updated package version to 4.2.0
• Improved getBalances utility helper
• Added 1271 Signature support
• Added withdrawal utility helper
• Reduced bundle size
• Integrated AAErrors
• Added 6492 Signature support
• Added Token Balances to getSupportedTokens payload
• Added gas estimates utility helper
• Modernized tooling
• Added various development tools and checks

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[github-actions[bot]]

size-limit report 📦

Path	Size
core (esm)	52.01 KB (+0.1% 🔺)
core (cjs)	56.5 KB (-0.04% 🔽)
account (tree-shaking)	50.95 KB (-0.01% 🔽)
bundler (tree-shaking)	2.33 KB (0%)
paymaster (tree-shaking)	2.25 KB (0%)
modules (tree-shaking)	40.05 KB (0%)