Release v0.3.0

Added

• Add configurable message submission retry and retry delay flag with default
  setting of two retries, two seconds apart
• golangci-lint config file created with current linters + scopelint
  linter enabled

Changed

• config subpackage moved into internal subdirectory to make it private to
  this project
• send2teams app moved into cmd subdirectory structure

Fixed

• Restore version embedding broken in v0.2.5
• Bump copyright year

References

• See the v0.3.0 milestone for the issues associated with this release.
• See our CHANGELOG for more information.