fix update-translations.py to work correctly with % at the end of a string

contrib/devtools/update-translations.py

@@ -49,7 +49,10 @@ def find_format_specifiers(s):
         percent = s.find('%', pos)
         if percent < 0:
             break
-        specifiers.append(s[percent+1])
+        try:
+            specifiers.append(s[percent+1])
+        except:
+            print('Failed to get specifier')
         pos = percent+2
     return specifiers