Switch pytest build action to use Python 3.9

Author: cgmorton

.github/workflows/build.yml

@@ -9,10 +9,10 @@ jobs:
 
     steps:
     - uses: actions/checkout@v1
-    - name: Set up Python 3.7
+    - name: Set up Python 3.9
       uses: actions/setup-python@v1
       with:
-        python-version: 3.7
+        python-version: 3.9
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip

setup.py

@@ -46,9 +46,11 @@ def find_version(*file_paths):
     tests_require=['pytest', 'pytest-cov'],
     packages=['openet.core'],
     keywords='OpenET Evapotranspiration Earth Engine',
-    classifiers = [
+    classifiers=[
         'License :: OSI Approved :: Apache Software License',
-        'Programming Language :: Python :: 3.7',
+        'Programming Language :: Python :: 3.8',
+        'Programming Language :: Python :: 3.9',
+        'Programming Language :: Python :: 3.10',
     ],
     zip_safe=False,
 )