Fix CI

Author: isuruf

bin/install_travis.sh

@@ -2,7 +2,7 @@
 
 # symengine's bin/install_travis.sh will install miniconda
 
-export conda_pkgs="python=${PYTHON_VERSION} pip 'cython>=0.29.24' pytest gmp mpfr"
+export conda_pkgs="python=${PYTHON_VERSION} pip pytest gmp mpfr"
 
 if [[ "${WITH_NUMPY}" != "no" ]]; then
     export conda_pkgs="${conda_pkgs} numpy";
@@ -27,7 +27,7 @@ if [[ "${WITH_SAGE}" == "yes" ]]; then
     export conda_pkgs="${conda_pkgs} sage=8.1";
 fi
 
-conda install -q ${conda_pkgs}
+conda install -q ${conda_pkgs} "cython>=0.29.24"
 
 if [[ "${WITH_SYMPY}" != "no" ]]; then
     pip install sympy;