v0.5.3

Breaking:

• Renamed logLevel to restrictedToMinimumLevel in LoggerConfiguration to be
  consistent with the serilog recommendation. Thanks @tsackey.

Changes:

• Bump dependency on Serilog.Sinks.PeriodicBatching to 3.1.0.

Fixes:

• Disable keep-alive in HttpClient.
• Makes the number of retries configurable before the IDataDogClient gives up
  logging by adding a new DataDogConfiguration.MaxRetries property. Thanks @dmitrynovik.