Update prost and prost-types to version 0.8

[romac]

Closes: #925

• 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 #926 (ee16e7c) into master (7b84781) will decrease coverage by 0.1%.
The diff coverage is 100.0%.

@@           Coverage Diff            @@
##           master    #926     +/-   ##
========================================
- Coverage    70.6%   70.4%   -0.2%     
========================================
  Files         203     203             
  Lines       16242   16278     +36     
========================================
+ Hits        11469   11470      +1     
- Misses       4773    4808     +35     

Impacted Files	Coverage Δ
tendermint/src/time.rs	93.2% <100.0%> (ø)
tendermint/src/moniker.rs	70.0% <0.0%> (-30.0%)	⬇️
tendermint/src/vote/power.rs	58.1% <0.0%> (-4.4%)	⬇️
tendermint/src/config.rs	64.3% <0.0%> (-1.6%)	⬇️
abci/src/server.rs	9.8% <0.0%> (-0.8%)	⬇️
light-client/src/macros.rs	10.3% <0.0%> (-0.1%)	⬇️
light-client/src/errors.rs	3.0% <0.0%> (ø)
light-client/src/types.rs	30.7% <0.0%> (+0.6%)	⬆️
testgen/src/header.rs	78.8% <0.0%> (+0.6%)	⬆️
testgen/src/vote.rs	84.6% <0.0%> (+0.8%)	⬆️
... and 3 more

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[xla]

🛅 🐑 🌫 ☀️

[xla]

Wondering what's going on with the docs check.

[romac]

Wondering what's going on with the docs check.

Looks like a transient issue, will re-run the jobs.