⚡ Align partial sign with Web3.js

[GabrielePicco]

Align partial sign with Web3.js version, including fix from the original Solnet codebase

⚠️ NOTE: Use notes like this to emphasize something important about the PR.

This could include other PRs this PR is built on top of; API breaking changes; reasons for why the PR is on hold; or anything else you would like to draw attention to.

Status	Type	⚠️ Core Change
Ready	Bug	No

Problem

Partial signature was not aligned with Web3.js

[coveralls]

Pull Request Test Coverage Report for Build 3121218885

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 21 of 22 (95.45%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.04%) to 80.875%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/Solana.Unity.Rpc/Builders/MessageBuilder.cs	10	11	90.91%

Totals
Change from base Build 3119685259:	-0.04%
Covered Lines:	6544
Relevant Lines:	7841

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💛 - Coveralls