Fix loading of template resources from relative paths

[philippjfr]

Fixes #2066

[philippjfr]

@xavArtley Do you know what this error is about?

ValueError: VTKVolume pane does not support objects of type 'UniformGrid'.

[xavArtley]

May be but I don't understand the link with this issue

[philippjfr]

There isn't one, all PRs are currently failing due to this error.

[xavArtley]

May be a change in pyvista version?

[xavArtley]

It's strange I installed latest pyvista version but it should not raise error

[xavArtley]

I think it's indirectly related to pyvista
the VTKVolume.applies test if vtk is in sys.module
I suppose vtk was imported when pyvista was but now it is not imported anymore and VTKVolume.applies return False

[codecov]

Codecov Report

Merging #2067 (d77f477) into master (8a233ca) will decrease coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2067      +/-   ##
==========================================
- Coverage   84.43%   84.39%   -0.04%     
==========================================
  Files         178      178              
  Lines       20636    20636              
==========================================
- Hits        17423    17415       -8     
- Misses       3213     3221       +8     

Impacted Files	Coverage Δ
panel/template/base.py	79.85% <100.00%> (ø)
panel/tests/pane/test_base.py	88.23% <0.00%> (-11.77%)	⬇️
panel/io/reload.py	64.36% <0.00%> (-2.30%)	⬇️
panel/pane/base.py	90.61% <0.00%> (-0.94%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 8a233ca...d77f477. Read the comment docs.