build(deps): bump pydata-sphinx-theme from 0.15.3 to 0.15.4 in /_package

Bumps [pydata-sphinx-theme](https://github.com/pydata/pydata-sphinx-theme) from 0.15.3 to 0.15.4.
- [Release notes](https://github.com/pydata/pydata-sphinx-theme/releases)
- [Changelog](https://github.com/pydata/pydata-sphinx-theme/blob/main/RELEASE.md)
- [Commits](pydata/pydata-sphinx-theme@v0.15.3...v0.15.4)

---
updated-dependencies:
- dependency-name: pydata-sphinx-theme
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

_package/pyproject.toml

@@ -44,7 +44,7 @@ doc = [
     "parse==1.20.2",
     "pypandoc==1.13",
     "pytest-sphinx==0.6.3",
-    "pydata_sphinx_theme==0.15.3",
+    "pydata_sphinx_theme==0.15.4",
     "sphinx-autobuild==2024.4.16",
     "sphinx-autodoc-typehints==2.2.2",
     "sphinx-copybutton==0.5.2",