Fix multiple bugs in Go SDK, Node.js SDK, and README [TestingNotRequired]

[AasishDairelSahayaGrinspan]

This PR fixes several bugs across the Go SDK, Node.js SDK, and the README documentation.

Fixed bugs:

1. Go SDK: Replaced deprecated ioutil package with io and os for better compatibility.
2. Go SDK: Fixed ioutil.NopCloser reference in tests to use io.NopCloser.
3. Node.js SDK: Corrected validation logic in validator.js.
4. Node.js SDK: Fixed bank lookup logic to handle edge cases correctly.
5. README: Updated outdated setup instructions for the Node.js library.
6. README: Fixed broken links in the Go SDK section.
7. Go SDK: Fixed error handling in client requests.
8. Node.js SDK: Improved performance of the search functionality.

[AasishDairelSahayaGrinspan]

/TestingNotRequired

[anfaas1618]

@byalaburgi @PriyankaMarbill can we merge this ? anything blocking this ?

[anfaas1618]

@AasishDairelSahayaGrinspan add label field -> TestingNotRequired

[AasishDairelSahayaGrinspan]

@AasishDairelSahayaGrinspan add label field -> TestingNotRequired

Hi @anfaas1618, sorry for the trouble! I don't have write access to apply labels on this PR. Could you please add the TestingNotRequired label? Thank you!