use ret instead of 0 return

[Eikix]

closes #704

[ClementWalter]

just use when we had to built a return struct or type, but don't add new returns

[Eikix]

just use when we had to built a return struct or type, but don't add new returns

thanks, done

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 18 lines in your changes missing coverage. Please review.

Project coverage is 66.28%. Comparing base (7321d91) to head (c5fa531).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
cairo/ethereum/cancun/transactions_types.cairo	0.00%	9 Missing ⚠️
cairo/ethereum/cancun/state.cairo	0.00%	2 Missing ⚠️
cairo/ethereum/cancun/transactions.cairo	0.00%	2 Missing ⚠️
cairo/ethereum/cancun/trie.cairo	0.00%	2 Missing ⚠️
cairo/ethereum_rlp/rlp.cairo	0.00%	2 Missing ⚠️
cairo/ethereum/cancun/utils/address.cairo	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #705      +/-   ##
==========================================
+ Coverage   66.21%   66.28%   +0.06%     
==========================================
  Files          88       88              
  Lines       20493    20527      +34     
==========================================
+ Hits        13570    13606      +36     
+ Misses       6923     6921       -2     

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