chore(release): mark pythonlib 0.5.6 as a pre-release (0.5.6b1)

Pairs the library with the browser: v152.0.4-beta.30 is published as a GitHub
pre-release, so the library that requires it should be one too.

PEP 440 puts 0.5.6b1 after 0.5.5 and before 0.5.6, and pip skips pre-releases
by default -- so `pip install camoufox` still resolves 0.5.5, and only
`pip install --pre camoufox` or an explicit pin picks this up. That is what
makes the conditional browser floor safe to exercise in the wild: the users who
opt in are the ones who get moved to beta.30.

Verified against the live release: with Playwright 1.61 installed the effective
floor resolves to beta.30 and the fetcher selects the real published asset
(camoufox-152.0.4-beta.30-lin.x86_64.zip). 172 tests pass, the 3.8 vermin gate
holds, and the package builds as camoufox-0.5.6b1.

Known wrinkle, not introduced here: _parse_semver() does int("6b1"), fails, and
substitutes 0, so 0.5.6b1 parses to (0, 5, 0). The browser constraint still
resolves correctly because repos.yml's only entry is min 0.5.0 / max 1, but a
future entry gating on a patch version would silently miss a pre-release
install. Worth making that parser PEP 440-aware separately.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

pythonlib/pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "poetry.core.masonry.api"
 
 [tool.poetry]
 name = "camoufox"
-version = "0.5.6"
+version = "0.5.6b1"
 description = "Wrapper around Playwright to help launch Camoufox"
 authors = ["daijro <daijro.dev@gmail.com>"]
 license = "MIT"