Use pyvista[test] to install pyvista test dependencies

.github/workflows/ci_cd.yml

@@ -159,7 +159,7 @@ jobs:
         run: pip install -ve .
         working-directory: pyvista
       - name: Install pyvista test requirements
-        run: pip install -v -r requirements_test.txt
+        run: pip install -v pyvista[test]
         working-directory: pyvista
       - name: Install pytest-pyvista
         run: pip install -ve .