chore(deps-dev): bump tsdown from 0.19.0 to 0.20.1

Bumps [tsdown](https://github.com/rolldown/tsdown) from 0.19.0 to 0.20.1.
- [Release notes](https://github.com/rolldown/tsdown/releases)
- [Commits](rolldown/tsdown@v0.19.0...v0.20.1)

---
updated-dependencies:
- dependency-name: tsdown
  dependency-version: 0.20.1
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

package.json

@@ -66,7 +66,7 @@
     "@types/node": "25.0.10",
     "@types/swagger2openapi": "7.0.4",
     "axios": "1.13.3",
-    "tsdown": "0.19.0",
+    "tsdown": "0.20.1",
     "typedoc": "0.28.16",
     "vitest": "4.0.18"
   },