deps: Update dependency blacken-docs to >=1.20.0,<2 (data-apis#439)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

pyproject.toml

@@ -70,7 +70,7 @@ lefthook = ">=1.13.1,<2"
 ruff = ">=0.12.12,<0.13"
 typos = ">=1.36.2,<2"
 actionlint = ">=1.7.7,<2"
-blacken-docs = ">=1.19.1,<2"
+blacken-docs = ">=1.20.0,<2"
 pytest = ">=8.4.2,<9"
 validate-pyproject = ">=0.24.1,<0.25"
 # NOTE: don't add cupy, jax, pytorch, or sparse here,