message: gas-oracle: fix average block gas limit flag
  The average block gas limit was converted to a uint64
  from a float64, this commit updates the flag parsing
  to parse the correct type.
diff: @@ -77,7 +77,7 @@ var (
  Usage: "max percent change of gas price per second",
  EnvVar: "GAS_PRICE_ORACLE_MAX_PERCENT_CHANGE_PER_EPOCH",
  }
  - AverageBlockGasLimitPerEpochFlag = cli.Float64Flag{
  + AverageBlockGasLimitPerEpochFlag = cli.Uint64Flag{
  Name: "average-block-gas-limit-per-epoch",
  Value: 11_000_000,
  Usage: "average block gas limit per epoch",
  