The include-what-you-use workflow fails with
```
Invalid workflow file: .github/workflows/iwyu.yaml#L25
The workflow is not valid. .github/workflows/iwyu.yaml (Line: 25, Col: 3): Error calling workflow 'scylladb/scylladb/.github/workflows/read-toolchain.yaml@257054deffbef0bde95f0428dc01ad10d7b30093'. The nested job 'read-toolchain' is requesting 'contents: read', but is only allowed 'contents: none'.
```
Fix by adding the correct permissions.
Closesscylladb/scylladb#28390