Fix and update build step for Python2.7 (dropbox#326)

* Pin pytest runner version
* Update workflow step naming

Author: eugeneyche

.github/workflows/pypiupload.yml

@@ -16,7 +16,7 @@ jobs:
 
     steps:
     - uses: actions/checkout@v2
-    - name: Publish to PyPi
+    - name: Setup Python
       uses: actions/[email protected]
       with:
         python-version: ${{ matrix.python-version }}

setup.py

@@ -31,7 +31,9 @@
 ]
 
 setup_requires = [
-    'pytest-runner',
+    # Pin pytest-runner to 5.2.0, since 5.3.0 uses `find_namespaces` directive, not supported in
+    # Python 2.7
+    'pytest-runner == 5.2.0',
 ]
 
 test_reqs = [