Update ERC-4337: Fix typo of 'bunder' to 'bundler'

[PatrickAlphaC]

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[eip-review-bot]

File ERCS/erc-4337.md

Requires 1 more reviewers from @drortirosh, @forshtat, @kristofgazso, @shahafn, @tjade273, @vbuterin, @yoavw