Upgrade EVMC to 8.0.0

[chfast]

https://github.com/ethereum/evmc/releases/tag/v8.0.0

[codecov]

Codecov Report

Merging #309 (3c9ea6d) into master (3361221) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #309   +/-   ##
=======================================
  Coverage   99.76%   99.76%           
=======================================
  Files          24       24           
  Lines        3831     3831           
=======================================
  Hits         3822     3822           
  Misses          9        9           

Flag	Coverage Δ
consensus	99.17% <100.00%> (ø)
unittests	99.76% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
lib/evmone/instructions.cpp	100.00% <ø> (ø)
lib/evmone/baseline.cpp	99.82% <100.00%> (ø)
lib/evmone/instructions.hpp	100.00% <100.00%> (ø)
test/unittests/evm_test.cpp	99.69% <100.00%> (ø)
test/utils/bytecode.hpp	100.00% <100.00%> (ø)