Do not install cython into the venv

Signed-off-by: Jono Yang <jyang@nexb.com>

Author: JonoYang

configure

@@ -242,7 +242,6 @@ create_virtualenv() {
             --no-vcs-ignore \
             $CFG_QUIET \
             "$CFG_ROOT_DIR/$VENV_DIR"
-        "$CFG_BIN_DIR/pip" install cython
     fi
 }
 

pyproject.toml

@@ -1,5 +1,5 @@
 [build-system]
-requires = ["cython", "setuptools", "wheel"]
+requires = ["setuptools", "wheel"]
 build-backend = "setuptools.build_meta"
 
 [tool.setuptools_scm]