Test: use newer NumPy version in recent Python versions.

Tools/ci-run.sh

@@ -54,7 +54,7 @@ if [ -z "${PYTHON_VERSION##2.7}" ]; then
   pip install -r test-requirements-27.txt || exit 1
 
 elif [ -n "${PYTHON_VERSION##*-dev}" ]; then
-  python -m pip install -r test-requirements.txt || exit 1
+  python -m pip install -r test-requirements.txt $(if [ -z "${PYTHON_VERSION##3.[45]*}" ]; then echo "'numpy<1.19.0'"; fi) || exit 1
 
   if [ "${PYTHON_VERSION##pypy*}" -a "${PYTHON_VERSION##3.[4789]*}" ]; then
     python -m pip install -r test-requirements-cpython.txt || exit 1

test-requirements.txt

-numpy < 1.19.0
+numpy
 coverage
 pycodestyle