chore: update toolkit to 4.9.1 in release.yml (#1560)

## Summary

- Updates `release.yml` toolkit reference from `4.9.0` → `4.9.1`
- `4.9.1` fixes the `pcu release attest` flag: `--crate-tag-prefix` now
correctly placed on the `attest` subcommand, unblocking the SLSA
attestation step that was failing with "required argument not provided"

## Test plan
- [ ] Re-run release pipeline — `release-hcaptcha_derive` and
`release-hcaptcha` both complete including attestation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Author: jerusdp

.circleci/release.yml

@@ -19,7 +19,7 @@ parameters:
     description: "Override workspace v* version (empty = nextsv auto-detect)"
 
 orbs:
-  toolkit: jerus-org/circleci-toolkit@4.9.0
+  toolkit: jerus-org/circleci-toolkit@4.9.1
 
 jobs:
   tools: