meta: Add audit config

[xla]

Add an explicit audit config to control its behaviour, also ignore
advisory for serde_cbor until resolved.

Signed-off-by: xla self@xla.is

• Referenced an issue explaining the need for the change
• Updated all relevant documentation in docs
• Updated all code comments where relevant
  * [ ] Wrote tests
  * [ ] Added entry in .changelog/

[codecov-commenter]

Codecov Report

Merging #1119 (38a97b5) into master (d2b9f33) will decrease coverage by 0.0%.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           master   #1119     +/-   ##
========================================
- Coverage    64.8%   64.7%   -0.1%     
========================================
  Files         240     240             
  Lines       20822   20822             
========================================
- Hits        13500   13492      -8     
- Misses       7322    7330      +8     

Impacted Files	Coverage Δ
testgen/src/vote.rs	84.0% <0.0%> (-1.7%)	⬇️
abci/src/codec.rs	87.8% <0.0%> (-1.4%)	⬇️
p2p/src/secret_connection/protocol.rs	59.8% <0.0%> (-1.0%)	⬇️
light-client-verifier/src/types.rs	38.2% <0.0%> (-0.9%)	⬇️
testgen/src/validator.rs	86.7% <0.0%> (-0.8%)	⬇️
testgen/src/commit.rs	90.6% <0.0%> (-0.7%)	⬇️
testgen/src/light_block.rs	76.1% <0.0%> (-0.6%)	⬇️
abci/src/server.rs	8.8% <0.0%> (-0.4%)	⬇️
tendermint/src/node.rs	63.6% <0.0%> (-0.2%)	⬇️
tendermint/src/evidence.rs	25.3% <0.0%> (+3.7%)	⬆️

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[thanethomson]

Nice, thanks!