gh-37230: some cython-lint fixes in ecl lib
    
a few details as suggested by `cython-lint` and `pycodestyle` in
`libs/ecl.pyx`

### 📝 Checklist

- [x] The title is concise, informative, and self-explanatory.
- [x] The description explains in detail what this PR is about.
    
URL: #37230
Reported by: Frédéric Chapoton
Reviewer(s): David Coudert

Author: Release Manager