Correct hint to pip install xlsxwriter

Author: altendky

canmatrix/exportall.py

@@ -35,7 +35,7 @@
 try:
     from .exportxlsx import *
 except:
-    logger.warn("no xlsx-export-support, some dependencies missing...  try pip install xlswriter")
+    logger.warn("no xlsx-export-support, some dependencies missing...  try pip install xlsxwriter")
 
 try:
     from .exportyaml import *