build(deps): bump ansys-sphinx-theme from 1.1.1 to 1.2.6

Bumps [ansys-sphinx-theme](https://github.com/ansys/ansys-sphinx-theme) from 1.1.1 to 1.2.6.
- [Release notes](https://github.com/ansys/ansys-sphinx-theme/releases)
- [Commits](ansys/ansys-sphinx-theme@v1.1.1...v1.2.6)

---
updated-dependencies:
- dependency-name: ansys-sphinx-theme
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

pyproject.toml

@@ -86,7 +86,7 @@ test-extra = [
     "ansys-dpf-core==0.13.0",
 ]
 doc = [
-    "ansys-sphinx-theme==1.1.1",
+    "ansys-sphinx-theme==1.2.6",
     "numpydoc==1.8.0",
     "pillow==10.4.0",
     "docker>=7.1.0",
@@ -101,7 +101,7 @@ dev = [
     "ipdb",
     "ipython",
     "whatsonpypi",
-    "ansys-sphinx-theme==1.1.1",
+    "ansys-sphinx-theme==1.2.6",
     "numpy>=1.23.5,<3",
     "numpydoc==1.8.0",
     "pillow==10.4.0",