update buf.yaml dependencies

[dssei]

Describe your changes and provide context

Update buf.yaml dependencies to point to buf.build/sei-protocol/cosmos-sdk rather than buf.build/cosmos/cosmos-sdk

This PR should fix https://github.com/sei-protocol/sei-chain/actions/runs/10966410259

Testing performed to validate your change

• local buf linting
• buf push (from local)
• ignite generate proto-go

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.07%. Comparing base (ad02ac6) to head (a011c40).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1868      +/-   ##
==========================================
+ Coverage   61.03%   61.07%   +0.04%     
==========================================
  Files         261      261              
  Lines       23100    23100              
==========================================
+ Hits        14098    14108      +10     
+ Misses       8009     7999      -10     
  Partials      993      993              

Flag	Coverage Δ
	61.07% <ø> (+0.04%)	⬆️

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see 1 file with indirect coverage changes