Update dependencies (#577)

* Update sphinx_gallery from 0.6.2 to 0.7.0

* Update pytest from 5.4.2 to 5.4.3

* Update importlib-metadata from 1.6.0 to 1.7.0

* Update tox from 3.15.0 to 3.16.0

* Update tox from 3.15.0 to 3.16.1

* reverted pre-commit to 1.21.0

* Update pre-commit from 2.5.1 to 2.6.0

* Doing an experiment to see if the newly released 2.6.0 works

* reverting pre-commit back

Co-authored-by: pyup-bot <github-bot@pyup.io>

dev-requirements.txt

@@ -1,13 +1,13 @@
-pre-commit==2.5.1
+pre-commit==1.21.0
 bumpversion==0.6.0
 codecov==2.1.7
-importlib-metadata==1.6.0
-pytest==5.4.2
+importlib-metadata==1.7.0
+pytest==5.4.3
 pytest-vcr==1.0.2
 sphinx==3.1.1
 pytest-cov==2.10.0
 sphinx-autobuild==0.7.1
-sphinx_gallery==0.6.2
+sphinx_gallery==0.7.0
 sphinx_rtd_theme==0.5.0
-tox==3.15.0
+tox==3.16.1
 pip>=19.0