Bump tools/swift-sdk-generator from a9f8e2a to a0ff972

Bumps [tools/swift-sdk-generator](https://github.com/apple/swift-sdk-generator) from `a9f8e2a` to `a0ff972`.
- [Commits](swiftlang/swift-sdk-generator@a9f8e2a...a0ff972)

---
updated-dependencies:
- dependency-name: tools/swift-sdk-generator
  dependency-type: direct:production
...

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

Author: dependabot[bot]