v5.1.0 release notes

• Validation:
  • new validator DoesntStartWith.
  • new validator DoesntEndWith.
  • new validator KeysIn.
• Configuration: added a Required flag for entries to prevent nil values.
• Compress middleware: the order of the Encoders now determines server-side priority, which will help chose an encoder when there are client priority ties.
• Optimization: use a sync.Pool for requests and responses for a small performance improvement.
• util/httputil.ParseMultiValuesHeader:
  • The input header is now trimmed
  • The function returns an empty slice if the input is empty
  • Minor optimization