Dev requirement update

requirements_dev.txt

@@ -1,17 +1,17 @@
 bump2version==1.0.0
-coverage==5.1
+coverage==5.2
 edx-sphinx-theme==1.5.0
 flake8==3.8.3
-ipython==7.15.0
-isort==4.3.21
+ipython==7.16.1
+isort==5.0.9
 pip==20.1.1
 PyInstaller==3.6
 pytz==2020.1
-requests==2.23.0
+pytest==5.4.3
 responses==0.10.15
-setuptools==47.1.1
-Sphinx==3.1.1
-tox==3.15.2
-twine==3.1.1
-watchdog==0.10.2
+setuptools==49.2.0
+Sphinx==3.1.2
+tox==3.16.1
+twine==3.2.0
+watchdog==0.10.3
 wheel==0.34.2