add py37 to manylinux builds

.manylinux-install.sh

@@ -7,7 +7,8 @@ for PYBIN in /opt/python/*/bin; do
     if [[ "${PYBIN}" == *"cp27"* ]] || \
        [[ "${PYBIN}" == *"cp34"* ]] || \
        [[ "${PYBIN}" == *"cp35"* ]] || \
-       [[ "${PYBIN}" == *"cp36"* ]]; then
+       [[ "${PYBIN}" == *"cp36"* ]] || \
+       [[ "${PYBIN}" == *"cp37"* ]]; then
         "${PYBIN}/pip" install -e /io/
         "${PYBIN}/pip" wheel /io/ -w wheelhouse/
 	rm -rf /io/build /io/*.egg-info