fix: copy only signed headers

[zirkelc]

Copy only signed headers to avoid mutation the body (see #19)

[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🟢	Lines	100% (🎯 80%)	97 / 97
🟢	Statements	100% (🎯 80%)	97 / 97
🟢	Functions	100% (🎯 80%)	3 / 3
🟢	Branches	94.73% (🎯 80%)	36 / 38

File Coverage

File	Stmts	Branches	Functions	Lines	Uncovered Lines
Changed Files
src/create-signed-fetcher.ts	100%	60%	100%	100%

Generated in workflow #94 for commit 92f4e77 by the Vitest Coverage Report Action

[pkg-pr-new]

Open in Stackblitz

pnpm add https://pkg.pr.new/zirkelc/aws-sigv4-fetch@24

commit: 92f4e77