Make font search case insensitive in logo example

Made check lowercase b/c on windows findfont returns a lowercase file name string such that the if statements can't evaluate true.

Author: story645

galleries/examples/misc/logos2.py

@@ -21,10 +21,10 @@
 def get_font_properties():
     # The original font is Calibri, if that is not installed, we fall back
     # to Carlito, which is metrically equivalent.
-    if 'Calibri' in matplotlib.font_manager.findfont('Calibri:bold'):
+    if 'calibri' in matplotlib.font_manager.findfont('Calibri:bold').lower():
         return matplotlib.font_manager.FontProperties(family='Calibri',
                                                       weight='bold')
-    if 'Carlito' in matplotlib.font_manager.findfont('Carlito:bold'):
+    if 'carlito' in matplotlib.font_manager.findfont('Carlito:bold').lower():
         print('Original font not found. Falling back to Carlito. '
               'The logo text will not be in the correct font.')
         return matplotlib.font_manager.FontProperties(family='Carlito',