Fix logger.warning message

nabu/estimation/cor_sino.py

@@ -114,7 +114,7 @@ class SinoCor(object):
             self.cor_abs = (imax + window_width - 1.0) / 2
             self.cor_rel = self.cor_abs - self.sx / 2.0 - 1
         if imax < 1:
-            self.logger.warning("sliding width ", window_width, " seems too large!")
+            self.logger.warning(str("sliding width ", window_width, " seems too large!"))
         self.rcor_abs = round(self.cor_abs)
         return self.rcor_abs