Removed unused dependencies

Author: wouterj

_build/.requirements.txt

@@ -1,16 +1,7 @@
-alabaster==0.7.10
-Babel==2.4.0
 docutils==0.13.1
-imagesize==0.7.1
-Jinja2==2.10.1
-MarkupSafe==1.0
 Pygments==2.2.0
-pytz==2017.2
-requests==2.20.0
-six==1.10.0
-snowballstemmer==1.2.1
 sphinx==1.8.5
+sphinxcontrib-phpdomain==0.6.3
 git+https://github.com/fabpot/sphinx-php.git@v2.0.0#egg_name=sphinx-php
 jsx-lexer===0.0.8
-sphinxcontrib-phpdomain==0.6.3
 sphinx_rtd_theme==0.5.0