Update requirements

Generated from pipenv with:

  $ pipenv lock -r > requirements.txt
  $ pipenv lock -r -d > requirements-dev.txt

requirements-dev.txt

@@ -1,30 +1,28 @@
 -i https://pypi.org/simple
 atomicwrites==1.3.0
-attrs==19.1.0
+attrs==19.3.0
 backcall==0.1.0
-decorator==4.4.0
+decorator==4.4.1
 entrypoints==0.3
-flake8==3.7.8
-importlib-metadata==0.19 ; python_version < '3.8'
+flake8==3.7.9
 ipython-genutils==0.2.0
-ipython==7.7.0
+ipython==7.9.0
 jedi==0.15.1
 mccabe==0.6.1
 more-itertools==7.2.0
-packaging==19.1
+packaging==19.2
 parso==0.5.1
 pexpect==4.7.0 ; sys_platform != 'win32'
 pickleshare==0.7.5
-pluggy==0.12.0
-prompt-toolkit==2.0.9
+pluggy==0.13.0
+prompt-toolkit==2.0.10
 ptyprocess==0.6.0
 py==1.8.0
 pycodestyle==2.5.0
 pyflakes==2.1.1
 pygments==2.4.2
-pyparsing==2.4.2
-pytest==5.1.1
-six==1.12.0
-traitlets==4.3.2
+pyparsing==2.4.5
+pytest==5.2.3
+six==1.13.0
+traitlets==4.3.3
 wcwidth==0.1.7
-zipp==0.6.0