update dependencies (sphinx, jinja2, pytz, six, urllib3)

FIX: Graylog2#738

FIX: Graylog2#739

FIX: Graylog2#740

FIX: Graylog2#741

FIX: Graylog2#742

requirements.txt

@@ -9,25 +9,25 @@ docutils==0.15.2
 futures==3.1.1
 idna==2.8
 imagesize==1.1.0
-Jinja2==2.10.1
+Jinja2==2.10.3
 livereload==2.6.1
 MarkupSafe==1.1.1
 packaging==19.2
 pathtools==0.1.2
 port-for==0.3.1
 Pygments==2.4.2
 pyparsing==2.4.2
-pytz==2019.2
+pytz==2019.3
 PyYAML==5.1.2
 requests==2.22.0
 singledispatch==3.4.0.3
-six==1.12.0
+six==1.13.0
 snowballstemmer==2.0.0
-Sphinx==2.2.0
+Sphinx==2.2.1
 sphinx-autobuild==0.7.1
 sphinx-rtd-theme==0.4.3
 sphinxcontrib-websupport==1.1.2
 tornado==5.1.1
 typing==3.7.4
-urllib3==1.25.6
+urllib3==1.25.7
 watchdog==0.9.0