ci: use index-url on vtk-osmesa (#1255)

Co-authored-by: pyansys-ci-bot <[email protected]>

Author: RobPasMue

doc/source/changelog/1255.maintenance.md

@@ -0,0 +1 @@
+Use index-url on vtk-osmesa

tox.ini

@@ -87,7 +87,7 @@ commands =
 
     # Ensure vtk compatibility
     links,html: uv pip uninstall vtk
-    links,html: uv pip install --extra-index-url https://wheels.vtk.org vtk-osmesa==9.3.20240907.dev0
+    links,html: uv pip install --index-url https://wheels.vtk.org vtk-osmesa==9.3.20240907.dev0
 
     # Render documentation with desired builder
     links,html,pdf: sphinx-build -d "{toxworkdir}/doc_doctree" {env:SOURCE_DIR} "{toxinidir}/{env:BUILD_DIR}/{env:BUILDER}" {env:BUILDER_OPTS} -b {env:BUILDER}