fix: replace deprecated codec.ProtoMarshaler interface with proto.Message

[MozirDmitriy]

Description

• In testing/utils.go, replaced the parameter type in the UnmarshalMsgResponses function from codec.ProtoMarshaler to proto.Message and added the necessary import
• In e2e/testsuite/codec.go, also replaced the parameter type in the identically named function

Replacing the deprecated interface helps avoid potential issues in the future when codec.ProtoMarshaler might be completely removed from the codebase. Using the recommended proto.Message interface aligns with SDK development best practices.
The interface replacement maintains the same functionality as the implementation of the functions doesn't use any specific methods of the codec.ProtoMarshaler interface that aren't available in proto.Message.

---

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• Wrote unit and integration tests.
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[gjermundgaraba]

Sorry for the long wait here! Could you please also add a changelog entry for this under ### Testing API in CHANGELOG.md?

Otherwise, I think this looks good and useful 🙏 Thank you!

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 61.68%. Comparing base (4c6b78f) to head (71cfa18).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
e2e/testsuite/codec.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #8366   +/-   ##
=======================================
  Coverage   61.68%   61.68%           
=======================================
  Files         299      299           
  Lines       21494    21494           
=======================================
  Hits        13259    13259           
  Misses       7643     7643           
  Partials      592      592           

Flag	Coverage Δ
08-wasm	66.28% <ø> (ø)
e2e	1.18% <0.00%> (ø)
ibc-go	67.77% <ø> (ø)

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[MozirDmitriy]

Sorry for the long wait here! Could you please also add a changelog entry for this under ### Testing API in CHANGELOG.md?

Otherwise, I think this looks good and useful 🙏 Thank you!

Sorry for late answear, i've added changelog, thanks for review

[MozirDmitriy]

@DeshErBojhaa Yes, sorry

[gjermundgaraba]

Sorry for the long wait here! I had to fix some e2e tests to work with external contributors, but it runs fine now! Thanks for the contribution! 🙌

[DeshErBojhaa]

Thanks for the contribution.