Update pygments from 2.3.0 to 2.3.1

requirements/docs.txt

@@ -5,9 +5,9 @@ Jinja2==2.10 \
     --hash=sha256:74c935a1b8bb9a3947c50a54766a969d4846290e1e788ea44c1392163723c3bd \
     --hash=sha256:f84be1bb0040caca4cea721fcbbbbd61f9be9464ca236387158b0feea01914a4
 # Pygments is required by Sphinx
-Pygments==2.3.0 \
-    --hash=sha256:6301ecb0997a52d2d31385e62d0a4a4cf18d2f2da7054a5ddad5c366cd39cee7 \
-    --hash=sha256:82666aac15622bd7bb685a4ee7f6625dd716da3ef7473620c192c0168aae64fc
+Pygments==2.3.1 \
+    --hash=sha256:e8218dd399a61674745138520d0d4cf2621d7e032439341bc3f647bff125818d \
+    --hash=sha256:5ffada19f6203563680669ee7f53b64dabbeb100eb51b61996085e99c03b284a
 # Sphinx is required by sphinxcontrib-httpdomain
 Sphinx==1.8.2 \
     --hash=sha256:b348790776490894e0424101af9c8413f2a86831524bd55c5f379d3e3e12ca64 \