Got v15

[sindresorhus]

Some ideas. Probably in May 2026:

• Remove .cancel() method and .isCanceled property, in favor of signal option.
  • Also test/cancel.ts and CancelError
• Require Node.js 22.
• Use FormData global when targeting Node.js 18 #2077 (in a major release in case it has some subtle differences)
• Make strictContentLength option true by default.
• Change the pipe event handler to only copy headers that aren't already explicitly set (explicit headers take precedence over piped ones). This fixes the principle-of-least-surprise issue where users can't override piped headers. Change the default of copyPipedHeaders from true to false to eliminate the "magical" behavior - users who want header copying can opt-in explicitly. Update documentation to explain this is now opt-in behavior for proxy scenarios, and add migration guide explaining the breaking changes: (1) explicit headers now win over piped headers, and (2) automatic header copying is disabled by default.
• Use private class methods/properties internally.
• Update dependencies
• Change HTTPError<T = any> to HTTPError<T = unknown>
• Fix TODO comments that mention major version.
• Change Buffer usage to Uint8Array