MNT: Bump Bokeh dependency to 1.4.0 for previous commit

Author: kernc

setup.py

@@ -33,7 +33,7 @@
             'typing ; python_version < "3.5"',
             'numpy',
             'pandas >= 0.25.0, != 0.25.0',
-            'bokeh >= 1.1.0',
+            'bokeh >= 1.4.0',
         ],
         extras_require={
             'doc': [