build: Remove '--enable-cgal' option as not compatible with '--enable…

…-cgal-header-only'


From `./configure --help`:

```
  --enable-cgal           enables link with the CGAL library default=no
  --enable-cgal-header-only   enable build with header-only install of CGAL, e.g. as for CGALv5; in that case do not use --enable-cgal default=no
```

setup.py

@@ -77,7 +77,6 @@ def build_extensions(self):
                 "--disable-auto-ptr",
                 "--enable-allcxxplugins",
                 "--enable-cgal-header-only",
-                "--enable-cgal",
                 "--enable-swig",
                 "--enable-pyext",
                 f'LDFLAGS={env["LDFLAGS"]}',