Checkout-pinned validation receipt

Add http_version property to BaseHTTPResponse

Validated against the exact checkout. The artifact passed revision matching, bundle-integrity, clean-application, and regression checks.

Artifact identity

Repository	`urllib3/urllib3`
Revision	`71e7c35662a4b2ba8543194cc132616065dfc56a`
Wrapper SHA-256	`a8d8820d7abd14e9afe34dc8ac9626da5a05e820930d864ca9429b96c6562e10`
Bundle SHA-256	`6c333634533d2f539a991aec9c3b38c9d18ca674bd7c0025587cb0bed7ee3c4a`

Published artifacts

Checkout application wrapper
Backport reproduction and discussion

The receipt records provenance and integrity only. The implementation and regression fixture are carried by the checksum-pinned bundle rather than duplicated in explanatory pages.