rpcdaemon: enable weekly fuzzer job

[JacekGlen]

This enables weekly fuzzer jobs on CircleCi.

The previous builds were failing due to a linking error. The problem was that the original libFuzzer was built using libstdc++. The libraries attached here were built using libc++ and are compatible with the Silkworm build.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (29b40fc) 52.27% compared to head (5b569f7) 52.55%.
Report is 7 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1722      +/-   ##
==========================================
+ Coverage   52.27%   52.55%   +0.28%     
==========================================
  Files         596      596              
  Lines       44496    44496              
  Branches     6886     6886              
==========================================
+ Hits        23261    23387     +126     
+ Misses      19178    19045     -133     
- Partials     2057     2064       +7     

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