chore: fix flakey partialSign test

[jstarry]

Problem

There is a partialSign test which tries to cause an exception by changing the first value in a signature to 0 but sometimes that byte is already a 0 and no exception is thrown.

Summary of Changes

• Ensure that the test always throws an exception by using an invalid signature

Fixes #

[codecov]

Codecov Report

Merging #27770 (8eb18f1) into master (e779032) will increase coverage by 0.3%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master   #27770     +/-   ##
=========================================
+ Coverage    76.9%    77.2%   +0.3%     
=========================================
  Files          48       55      +7     
  Lines        2505     2889    +384     
  Branches      355      402     +47     
=========================================
+ Hits         1927     2232    +305     
- Misses        448      515     +67     
- Partials      130      142     +12