fix(wasm): [finix] add merchant source verification key

[Nithin1506200]

Type of Change

• Bugfix
• New feature
• Enhancement
• Refactoring
• Dependency updates
• Documentation
• CI/CD

Description

• No test needed , just adding webhook source verification WASM for this pr

Additional Changes

• This PR modifies the API contract
• This PR modifies the database schema
• This PR modifies application configuration/environment variables

Motivation and Context

How did you test it?

Checklist

• I formatted the code cargo +nightly fmt --all
• I addressed lints thrown by cargo clippy
• I reviewed the submitted code
• I added unit tests for my changes where possible

[semanticdiff-com]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (main@d9226b2). Learn more about missing BASE report.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #10792   +/-   ##
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  Coverage        ?    6.38%           
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  Files           ?     1268           
  Lines           ?   318670           
  Branches        ?        0           
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  Hits            ?    20353           
  Misses          ?   298317           
  Partials        ?        0           

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