fix(exc_handling): add missing Flags import

[spifory]

Rationale

When using 2.4.1a1, there is an error that gets raised during runtime when there is an error raised.

Summary of changes made

Adds the missing from .flags import Flags import as it is a missing import.

Checklist

• This PR changes the onami module/cog codebase
  • These changes add new functionality to the module/cog
  • These changes fix an issue or bug in the module/cog
  • I have tested that these changes work on a production bot codebase
  • I have tested these changes against the CI/CD test suite
  • I have updated the documentation to reflect these changes
• This PR changes the CI/CD test suite
  • I have tested my suite changes are well-formed (all tests can be discovered)
  • These changes adjust existing test cases
  • These changes add new test cases
• This PR changes prose (such as the documentation, README or other Markdown/RST documents)
  • I have proofread my changes for grammar and spelling issues
  • I have tested that any changes regarding Markdown/RST syntax result in a well formed document