[MNT] [Dependabot](deps-dev): Update sphinx-gallery requirement from …

…<0.15.0 to <0.16.0 (#247)

Updates the requirements on
[sphinx-gallery](https://github.com/sphinx-gallery/sphinx-gallery) to
permit the latest version.

pyproject.toml

@@ -71,7 +71,7 @@ docs = [
     "numpydoc",
     "pydata-sphinx-theme",
     "sphinx-issues<4.0.0",
-    "sphinx-gallery<0.15.0",
+    "sphinx-gallery<0.16.0",
     "sphinx-panels",
     "sphinx-design<0.6.0",
     "Sphinx<8.0.0,!=7.2.0",