MAINT: Bump panel from 1.4.1 to 1.4.2 in the docs-deps group

Bumps the docs-deps group with 1 update: [panel](https://github.com/holoviz/panel).


Updates `panel` from 1.4.1 to 1.4.2
- [Release notes](https://github.com/holoviz/panel/releases)
- [Changelog](https://github.com/holoviz/panel/blob/main/CHANGELOG.md)
- [Commits](holoviz/panel@v1.4.1...v1.4.2)

---
updated-dependencies:
- dependency-name: panel
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: docs-deps
...

Signed-off-by: dependabot[bot] <[email protected]>

pyproject.toml

@@ -54,7 +54,7 @@ tests = [
     "grpcio-health-checking==1.48.2",
     "numpy==1.26.4",
     "pandas==2.2.2",
-    "panel==1.4.1",
+    "panel==1.4.2",
     "platformdirs==4.2.0",
     "plotly==5.21.0",
     "protobuf==4.25.3",
@@ -71,7 +71,7 @@ doc = [
     "jupyter_sphinx==0.5.3",
     "matplotlib==3.8.4",
     "numpydoc==1.7.0",
-    "panel==1.4.1",
+    "panel==1.4.2",
     "phantomjs==1.4.1",
     "pypandoc==1.13",
     "pyvista==0.43.5",