bump ethers, remove upraises from callbacks (#664)

codex.nimble

@@ -12,7 +12,7 @@ requires "bearssl >= 0.1.4"
 requires "chronicles >= 0.7.2"
 requires "chronos >= 2.5.2"
 requires "confutils"
-requires "ethers >= 0.7.0 & < 0.8.0"
+requires "ethers >= 0.7.1 & < 0.8.0"
 requires "libbacktrace"
 requires "libp2p"
 requires "metrics"

codex/contracts/clock.nim

@@ -26,7 +26,7 @@ method start*(clock: OnChainClock) {.async.} =
   if clock.started:
     return
 
-  proc onBlock(blck: Block) {.upraises:[].} =
+  proc onBlock(blck: Block) =
     let blockTime = initTime(blck.timestamp.truncate(int64), 0)
     let computerTime = getTime()
     clock.offset = blockTime - computerTime