2.0.0: Credential functions

• Heads up: Refactored com.amazon.aws.credentials.Provider from an
  interface to an abstract base class!
  (@thekid)
• Implemented PR #11: Accept credential functions in ServiceEndpoint
  constructor
  (@thekid)

1.8.1: Headers signing fix

• Fixed issue #10: There were headers present in the request which were
  not signed
  (@thekid)
• Added the constant SignatureV4::NO_PAYLOAD which is equal to the pre-
  calculated sha256 hash of an empty string
  (@thekid)

1.8.0: Credential Provider

• Added CredentialProvider::none() which never provides any credentials
  (@thekid)
• Merged PR #9: Implement credential providers. Initial support for these
  providers: Environment variables, Shared credentials and config files
  and Amazon ECS container credentials.
  (@thekid)

1.7.0: Request streaming

• Merged PR #8: Add possibility to stream requests to AWS endpoints. Useful
  for transferring large payloads without blocking, e.g. S3 uploads.
  (@thekid)

1.6.0: XP 12 compatibility

• Made compatible with XP 12 - @thekid

1.5.0: User agent overwriting

• Added PHP 8.4 to the test matrix - @thekid
• Merged PR #6: Allow overwriting user agent via headers - @thekid

1.4.0: Marshalling library compatibility

• Added compatibility with xp-forge/marshalling v2.0.0 - @thekid

1.3.0: Signature API

• Merged PR #5: Move responsibility for processing headers to endpoint
  implementation
  (@thekid)

1.2.0: Sign links

• Merged PR #4: Implement signing a link, e.g. to share S3 resources. See
  https://docs.aws.amazon.com/AmazonS3/latest/userguide/ShareObjectPreSignedURL.html
  (@thekid)

1.1.0: Marshalling

• Merged PR #3: Marshal and unmarshal payloads. Adds a dependency on the
  xp-forge/marshalling library
  (@thekid)