Fix doctests

[thazhemadam]

julia> WS2_v = AtomGraph(joinpath("docs/src", "files", "mp-224.cif"), use_voronoi=true)

doesn't seem to work anymore, as it returns a missing instead of an AtomGraph.

The following error gets thrown -

BoundsError(([0.3716777477498808 0.0 0.0 0.9704476083038442 0.0 0.9704476083038442; 0.0 0.3716777477498808
0.9704476083038442 0.0 0.9704476083038442 0.0; 0.0 0.9704476083038442 1.0 0.0 0.02318554171415271
0.31893970588360054; 0.9704476083038442 0.0 0.0 1.0 0.31893970588360054 0.02318554171415271; 0.0
0.9704476083038442 0.02318554171415271 0.31893970588360054 1.0 0.0; 0.9704476083038442 0.0
0.31893970588360054 0.02318554171415271 0.0 1.0], ["W", "W", "S", "S", "S", "S"]), 3)

[codecov[bot]]

Codecov Report

Merging #126 (8b602d5) into main (0dd3b61) will not change coverage. The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #126   +/-   ##
=======================================
  Coverage   86.19%   86.19%           
=======================================
  Files          18       18           
  Lines         507      507           
=======================================
  Hits          437      437           
  Misses         70       70           

Impacted Files	Coverage Δ
src/utils/graph_building.jl	98.36% <100.00%> (ø)

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[rkurchin]

Okay, should we just merge this? I think at least fewer of them are failing than before... 🙄 though I'm sort of inclined to just ditch doctests given how finicky they are

[thazhemadam]

I think we should merge this for now. We can get back to the doctests later, but this also fixes up the problem of the docs not building at all IIRC. Either way, this has been around for a long time now and should probably be merged right away.