feat(WakuRln): zero indexed deployments and updated dependency

[rymnc]

• fix: update vacp2p/rln-contract submodule to downstream fix(rln): use zero-based indexing instead of 1-based indexing for commitments vacp2p/rln-contract#28
• feat(rln): zero indexed deployment

[github-actions]

LCOV of commit 8f8dda5 during CI #21

Summary coverage rate:
  lines......: 88.9% (32 of 36 lines)
  functions..: 90.9% (10 of 11 functions)
  branches...: 66.7% (12 of 18 branches)

Files changed coverage rate:
                               |Lines       |Functions  |Branches    
  Filename                     |Rate     Num|Rate    Num|Rate     Num
  ===================================================================
  contracts/WakuRln.sol        |88.2%     17|83.3%     6|66.7%      6