update meshcat submodule

[rdeits]

to get meshcat-dev/meshcat#29

cc @gizatt

[codecov-io]

Codecov Report

Merging #17 into master will increase coverage by 0.04%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #17      +/-   ##
==========================================
+ Coverage   87.41%   87.45%   +0.04%     
==========================================
  Files           8        8              
  Lines         572      574       +2     
==========================================
+ Hits          500      502       +2     
  Misses         72       72

Impacted Files	Coverage Δ
src/meshcat/tests/test_drawing.py	95.78% <100%> (+0.09%)	⬆️

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