fix: Fix incorrect calculation for the reserved size

[mauricefisher64]

Changes in this pull request

The default signers were not returning the correct reserve size

Checklist

• This PR represents a single feature, fix, or change.
• All applicable changes have been documented.
• Any TO DO items (or similar) have been entered as GitHub issues and the link to that issue has been included in a comment.

[codecov]

Codecov Report

Attention: Patch coverage is 30.76923% with 27 lines in your changes missing coverage. Please review.

Project coverage is 78.83%. Comparing base (9428dc7) to head (936b765).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...rc/raw_signature/openssl/signers/ed25519_signer.rs	0.00%	12 Missing ⚠️
...to/src/raw_signature/openssl/signers/rsa_signer.rs	0.00%	12 Missing ⚠️
.../src/raw_signature/openssl/signers/ecdsa_signer.rs	75.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #965      +/-   ##
==========================================
- Coverage   78.85%   78.83%   -0.02%     
==========================================
  Files         146      146              
  Lines       35213    35229      +16     
==========================================
+ Hits        27766    27773       +7     
- Misses       7447     7456       +9     

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