Bump flatbuffers

[PsiACE]

Signed-off-by: Chojan Shang psiace@outlook.com

Which issue does this PR close?

Closes #476

Reference rustsec/advisory-db#917 and Wait rustsec/advisory-db#943

Rationale for this change

On the one hand, we should pay attention to security issues. On the other hand, the new version may be better.

What changes are included in this PR?

Just bump flatbuffers and add unsafe mark .

Are there any user-facing changes?

No user-facing changes.

[codecov-commenter]

Codecov Report

Merging #499 (4defd62) into master (9723209) will increase coverage by 0.00%.
The diff coverage is 50.00%.

@@           Coverage Diff           @@
##           master     #499   +/-   ##
=======================================
  Coverage   82.62%   82.62%           
=======================================
  Files         165      165           
  Lines       45664    45664           
=======================================
+ Hits        37728    37729    +1     
+ Misses       7936     7935    -1     

Impacted Files	Coverage Δ
arrow/src/ipc/gen/SparseTensor.rs	0.00% <0.00%> (ø)
arrow/src/ipc/gen/Message.rs	34.40% <33.33%> (ø)
arrow/src/ipc/gen/Schema.rs	41.05% <65.00%> (ø)
parquet/src/encodings/encoding.rs	95.04% <0.00%> (+0.19%)	⬆️

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[alamb]

Thank you @PsiACE