MAINT: CI: Test with numpy back to 1.15.

Author: WarrenWeckesser

.github/workflows/pythonpackage.yml

@@ -10,6 +10,7 @@ jobs:
       max-parallel: 4
       matrix:
         python-version: [3.5, 3.6, 3.7]
+        numpy-version: [1.15, 1.16, 1.17]
 
     steps:
     - uses: actions/checkout@v1
@@ -20,7 +21,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install -r requirements.txt
+        pip install numpy==${{ matrix.numpy-version }}
     - name: Lint with flake8
       run: |
         pip install flake8

requirements.txt

@@ -1 +1 @@
-numpy>=1.17
+numpy>=1.15

setup.py

@@ -51,7 +51,7 @@ def get_version():
           packages=find_packages(exclude=['doc']),
           author='Travis E. Oliphant et al.',
           license='BSD',
-          install_requires=['numpy>=1.17'],
+          install_requires=['numpy>=1.15'],
           python_requires='>=3.5',
           classifiers=CLASSIFIERS.splitlines(),
           project_urls={