Update configuration file format for Tendermint v0.35

[thanethomson]

Follows from #1139

[codecov-commenter]

Codecov Report

Merging #1144 (262bf2b) into master (1a252a8) will decrease coverage by 0.0%.
The diff coverage is 79.7%.

@@           Coverage Diff            @@
##           master   #1144     +/-   ##
========================================
- Coverage    64.7%   64.7%   -0.1%     
========================================
  Files         231     232      +1     
  Lines       15637   15667     +30     
========================================
+ Hits        10122   10139     +17     
- Misses       5515    5528     +13     

Impacted Files	Coverage Δ
config/src/lib.rs	100.0% <ø> (ø)
config/src/config.rs	51.1% <35.7%> (-11.3%)	⬇️
config/src/serialization.rs	89.2% <89.2%> (ø)
testgen/src/vote.rs	84.0% <0.0%> (-1.7%)	⬇️
testgen/src/header.rs	88.1% <0.0%> (-0.7%)	⬇️
testgen/src/commit.rs	90.6% <0.0%> (-0.7%)	⬇️

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