build: output coverage report

[tplooker]

Tweaks to output the test coverage report

Description

Tweaks to output the test coverage report

• [ ] Tests for the changes have been added (for bug fixes / features)
• [x] The commit message(s) follow conventional commits
• [ ] Documentation has been added / updated (for bug fixes / features)
• [x] Changes follow the contributing document.

Motivation and Context

Test coverage

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No

Which merge strategy will you use?

• [x] Squash
• [ ] Rebase (REVIEW COMMITS)

[github-actions[bot]]

Total Coverage: 87.23%

Coverage Report

File	Branches	Funcs	Lines	Uncovered Lines
src
bbsSignature.ts	100%	72.73%	81.25%	140, 164, 222, 223, 224, 231, 242, 243, 260, 261, 262, 270
bls12381.ts	83.33%	100%	100%	26
bls12381toBbs.ts	100%	100%	100%
index.ts	100%	100%	100%
src/types
BlsKeyPair.ts	100%	100%	100%
index.ts	100%	100%	100%