v0.7.1.1

The same
libsecp256k1 0.7.1
(1a53f49) as v0.7.1, and the same bindings: no wrapper changed
behaviour, and nothing in the public API moved. What a fourth number
carries here is the floor the package is built on, its documentation,
and the gate around both.

• Dropped support for Python 3.9 (minimum is now 3.10): it reached end
  of life in October 2025, and keeping it held uv.lock at a second
  resolution of its own, cffi 2.1 requiring 3.10 and cffi 2.0 staying
  pinned for 3.9 alone. It also cost the build matrix its widest cell,
  CPython having no Windows arm64 build before 3.11
• Published documentation: a Sphinx build under docs/, served at
  Read the Docs, which the
  documentation metadata url now names instead of the README
• The distribution names The btclib developers as its author and ships
  AUTHORS.md beside LICENSE and COPYRIGHT. The licence header of
  every source file is the short MIT one, so the three no longer state
  the same holder and the same terms three different ways
• Three scheduled workflows join published, each asking on a morning
  of its own a question no pull request can: whether the urls in the
  prose still resolve (links), whether the tree survives every
  dependency at its newest (latest), and whether the suite would
  notice a wrong line (mutation). None of them gates a merge, and that
  is the design: what they report is the outside world moving, or a test
  nobody has written, and neither is something a branch can act on
• Each vendored test vector is pinned to a commit and a blob SHA-1 in
  tests/README.md, so a citation names the revision actually copied
  rather than a file that changes underneath it, and a monthly workflow
  opens an issue when upstream moves one
• New REPOSITORY.md: the branch rules, required checks, token
  permissions, publishing environments and scanning settings that live
  outside the tree and cannot be recovered by reading it, each with the
  API call that reads it back
• The pre-commit gate, which is the one definition of clean and what CI
  runs rather than a second list of its own, now also measures the yaml,
  the prose and the packaging metadata, and checks itself. mypy runs
  with more of its optional error codes and ruff with more rule-sets,
  every one of which the tree already satisfied
• More tests, and what each one verifies is now stated in its docstring
  and gated as such: the callbacks, the copyright headers, the
  documentation build and the vendored data are covered where they were
  not