docs: update requirements.txt

docs/requirements.txt

@@ -1,28 +1,20 @@
-Babel==2.5.1
-certifi==2017.11.5
+alabaster==0.7.12
+Babel==2.6.0
+certifi==2018.10.15
 chardet==3.0.4
-click==6.7
-colorclass==2.2.0
-cryptography==1.7.1
 docutils==0.14
-idna==2.6
-imagesize==0.7.1
+idna==2.7
+imagesize==1.1.0
 Jinja2==2.10
-keyring==10.1
-keyrings.alt==1.3
-MarkupSafe==1.0
-pyasn1==0.1.9
-pycrypto==2.6.1
+MarkupSafe==1.1.0
+packaging==18.0
 Pygments==2.2.0
-pygobject==3.22.0
-pytz==2017.3
-pyxdg==0.25
-requests==2.18.4
-SecretStorage==2.3.1
-six==1.10.0
+pyparsing==2.3.0
+pytz==2018.7
+requests==2.20.1
+six==1.11.0
 snowballstemmer==1.2.1
-Sphinx==1.6.5
-sphinx-rtd-theme==0.2.4
-sphinxcontrib-versioning==2.2.1
-sphinxcontrib-websupport==1.0.1
-urllib3==1.22
+Sphinx==1.8.2
+sphinx-rtd-theme==0.4.2
+sphinxcontrib-websupport==1.1.0
+urllib3==1.24.1