maint: bump ansys-sphinx-theme from 1.2.4 to 1.2.6 (#138)

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

requirements/requirements_doc.txt

@@ -1,4 +1,4 @@
-ansys-sphinx-theme==1.2.4
+ansys-sphinx-theme==1.2.6
 jupyterlab==4.3.1
 jupytext==1.16.6
 jupyter-server==2.15.0