pyo3-stub-gen-derive 0.23.0-1 packages the proc-macro crate used by
pyo3-stub-gen 0.23.0. It is needed for the pyo3-stub-gen dependency chain,
which in turn is needed by raygeo/rayforge packaging work.

Dependency notes:

* The normal RustPython parser dependency is now satisfiable from unstable:
  rust-rustpython-parser 0.4.0-1 and its rustpython-ast/parser-core
  dependencies are apt-visible on amd64.
* debian/patches/relax-dev-dependencies.patch relaxes only the test-only
  inventory dev-dependency from 0.3.24 to 0.3.21, matching the version
  currently packaged in Debian. This is not used by the library binary
  dependencies.
* Generated autopkgtests are marked flaky/broken in debcargo.toml because
  upstream's trybuild tests dev-depend on the sibling pyo3-stub-gen crate, and
  pyo3-stub-gen depends on this derive crate. This is a bootstrap cycle; the
  main pyo3-stub-gen package should cover the integration path once this derive
  crate is available.

Validation:

* DEBFULLNAME='Michele Cane' DEBEMAIL='michele.cane@proton.me'
  ./update.sh pyo3-stub-gen-derive succeeds with only the expected generated
  changelog distribution marker.
* ./build.sh pyo3-stub-gen-derive produced
  build/rust-pyo3-stub-gen-derive_0.23.0-1_amd64.changes. The binary build
  succeeded and integrated lintian reported worst tag warn.
* Autopkgtest initially failed because the generated tests require the sibling
  pyo3-stub-gen crate. After marking those generated tests flaky/broken, a
  retry was blocked by local unshare/sbuild testbed space exhaustion while
  installing dependencies, before package compilation:
  "No space left on device" in the cloned chroot and
  "Failed to explain bd-uninstallable". Non-interactive sudo is not available
  in this environment to clean the root-owned stale
  /var/lib/sbuild/build/reproducible-path directory.
* Explicit deep lintian:
  lintian --display-info --pedantic
  build/rust-pyo3-stub-gen-derive_0.23.0-1_amd64.changes
  Remaining tags are distribution-and-changes-mismatch for the generated
  UNRELEASED changelog distribution, extended-description-is-probably-too-short,
  package-contains-documentation-outside-usr-share-doc for the upstream README
  in the cargo registry source tree, upstream-metadata-missing-bug-tracking,
  and package-uses-old-debhelper-compat-version 13.

Reverse dependencies:

* dev/list-rdeps.sh pyo3-stub-gen-derive could not run locally because
  aptitude is not installed.
* No apt-visible archive package exists for pyo3-stub-gen-derive yet, so
  apt-cache reverse-dependency checks could not provide useful results.
