pin flatbuffers to 0.8.4

[ritchie46]

Fix for #238

[jorgecarleitao]

Thanks a lot, @ritchie46 , for your fast response and fix 👍

Let's hope that this is temporary and flatbuffers addresses this on their side of things.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.51%. Comparing base (ed00e4d) to head (b2cffc1).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #239      +/-   ##
==========================================
+ Coverage   82.49%   82.51%   +0.02%     
==========================================
  Files         162      162              
  Lines       43621    43655      +34     
==========================================
+ Hits        35983    36021      +38     
+ Misses       7638     7634       -4     

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[alamb]

merging to get CI green

[ritchie46]

Thanks for the quick merge on this one!