Bump exchange-calendars from 4.5.5 to 4.5.6 (#36)

Bumps [exchange-calendars](https://github.com/gerrymanoim/exchange_calendars) from 4.5.5 to 4.5.6.
- [Release notes](https://github.com/gerrymanoim/exchange_calendars/releases)
- [Changelog](https://github.com/gerrymanoim/exchange_calendars/blob/master/docs/changes_archive.md)
- [Commits](gerrymanoim/exchange_calendars@4.5.5...4.5.6)

---
updated-dependencies:
- dependency-name: exchange-calendars
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements.txt

@@ -4,5 +4,5 @@ pydantic==2.8.2
 uvicorn==0.30.5
 slowapi==0.1.9
 email-validator==2.2.0
-exchange_calendars==4.5.5
+exchange_calendars==4.5.6
 holidays==0.54