chore(deps): update pyvista requirement in /requirements

Updates the requirements on [pyvista](https://github.com/pyvista/pyvista) to permit the latest version.
- [Release notes](https://github.com/pyvista/pyvista/releases)
- [Commits](pyvista/pyvista@0.4.0...v0.48.4)

---
updated-dependencies:
- dependency-name: pyvista
  dependency-version: 0.48.4
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements/embedded.txt

@@ -1,4 +1,4 @@
-pyvista>=0.4 #3D visualisation/vtk meshing
+pyvista>=0.48.4 #3D visualisation/vtk meshing
 LoopStructural>=1.6.6 #3D geological modelling
 geoh5py>=0.9 #saving models to hdf5
 dill>=0.3.9     #saving models to python

requirements/testing.txt

@@ -3,7 +3,7 @@
 
 pytest-cov>=4
 packaging>=23
-pyvista>=0.4 #3D visualisation/vtk meshing
+pyvista>=0.48.4 #3D visualisation/vtk meshing
 LoopStructural>=1.6.23 #3D geological modelling
 geoh5py>=0.9 #saving models to hdf5
 dill>=0.3.9     #saving models to python