Remove unecessary environment variable from cibuildwheel config

Author: ksunden

.github/workflows/cibuildwheel.yml

@@ -64,9 +64,6 @@ jobs:
         run: |
           python -m build --sdist
           python ci/export_sdist_name.py
-        env:
-          # Prevent including development runtime dependencies in metadata.
-          CIBUILDWHEEL: 1
 
       - name: Check README rendering for PyPI
         run: twine check dist/*