fix(ci): add contents:write permission to release crates job (#77)

## Summary
- The `release` job in `release-crates.yml` sets job-level `permissions`
with only `id-token: write`, which **overrides** the workflow-level
permissions entirely (including `contents: write`)
- This caused release-plz to fail with `403 Forbidden` when trying to
create git tags via
`https://api.github.com/repos/Devolutions/cadeau/git/tags`
- Adds `contents: write` to the release job's permissions so tags can be
created

## Test plan
- [ ] Re-run the "Release crates" workflow after merge and verify the
git tag is created successfully

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

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: irvingoujAtDevolution

.github/workflows/release-crates.yml

@@ -43,6 +43,7 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       id-token: write
+      contents: write
 
     steps:
       - name: Checkout repository