Fix encoding for LaTeX

Instead of a combining acute accent, use a single-codepoint encoding

Author: jkseppan

doc/style_changes.rst

@@ -10,7 +10,7 @@ upcoming 2.0 release!
 The new default color map will be 'viridis' (aka `option
 D <http://bids.github.io/colormap/>`_).  For an introduction to color
 theory and how 'viridis' was generated watch Nathaniel Smith and
-Stéfan van der Walt's talk from SciPy2015
+Stéfan van der Walt's talk from SciPy2015
 
 .. raw:: html