Upgrade tabler to 1.0.0-beta21

### Proposed Changes

Upgrade [tabler](https://github.com/tabler/tabler) to its most recent release.

### Justification

[Version 1.0.0-beta21](https://github.com/tabler/tabler/releases/tag/v1.0.0-beta21) was released recently (after over a year since beta20). We're handling this out-of-band from our normal dependency updates to allow sufficient time to test for any cosmetic issues.