Fix signature for RLP encoding

[IAvecilla]

Trying to deploy in the new era-test-node, we discovered an issue related to the signature and the RLP encoding for the transaction. This PR fixes that error, enabling deployment in both local-setup (docker nodes) and the new memory node.

closes #97

[codecov-commenter]

Codecov Report

Merging #92 (b54a79f) into main (39f010b) will increase coverage by 0.23%.
Report is 3 commits behind head on main.
The diff coverage is 90.47%.

@@            Coverage Diff             @@
##             main      #92      +/-   ##
==========================================
+ Coverage   83.02%   83.26%   +0.23%     
==========================================
  Files          13       13              
  Lines        3170     3167       -3     
==========================================
+ Hits         2632     2637       +5     
+ Misses        538      530       -8     

Files Changed	Coverage Δ
src/zks_utils.rs	31.03% <ø> (ø)
src/zks_wallet/wallet.rs	85.40% <66.66%> (+0.14%)	⬆️
src/eip712/transaction_request.rs	92.85% <90.47%> (+3.03%)	⬆️
src/eip712/transaction.rs	83.40% <100.00%> (+0.64%)	⬆️
src/zks_provider/mod.rs	91.06% <100.00%> (-0.02%)	⬇️

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[jpcenteno]

I didn't see any new test. Did we had failing tests before these changes? In my opinion, bug fix PRs should include tests to ensure the bug does not happen again. This also provides the added value of providing a bug explanation for cases like this when we have to review a PR from a month ago.

[IAvecilla]

In terms of testing for this particular pull request, this fix specifically addresses the deploy feature in the memory node. To test it, you can change the ERA_CHAIN_ID to match the one in the memory node and set the environment variable to correspond to the memory node's URL.

Looking ahead, the plan could involve either migrating this testing procedure to the memory node directly or creating two distinct test suites—one for working with the node in a Docker environment and the other for the memory node.

[mationorato]

LGTM