Update sphinx from 1.7.6 to 1.7.7

requirements/docs.txt

@@ -9,9 +9,9 @@ Pygments==2.2.0 \
     --hash=sha256:78f3f434bcc5d6ee09020f92ba487f95ba50f1e3ef83ae96b9d5ffa1bab25c5d \
     --hash=sha256:dbae1046def0efb574852fab9e90209b23f556367b5a320c0bcb871c77c3e8cc
 # Sphinx is required by sphinxcontrib-httpdomain
-Sphinx==1.7.6 \
-    --hash=sha256:a765c6db1e5b62aae857697cd4402a5c1a315a7b0854bbcd0fc8cdc524da5896 \
-    --hash=sha256:217ad9ece2156ed9f8af12b5d2c82a499ddf2c70a33c5f81864a08d8c67b9efc
+Sphinx==1.7.7 \
+    --hash=sha256:a3defde5e17b5bc2aa21820674409287acc4d56bf8d009213d275e4b9d0d490d \
+    --hash=sha256:71531900af3f68625a29c4e00381bee8f85255219a3d500a3e255076a45b735e
 # alabaster is required by Sphinx
 alabaster==0.7.11 \
     --hash=sha256:674bb3bab080f598371f4443c5008cbfeb1a5e622dd312395d2d82af2c54c456 \