fix LOG.warn() deprecation warning

gramps/plugins/export/exportpkg.py

@@ -175,7 +175,7 @@ class PackageWriter:
         try:
             archive = tarfile.open(self.filename,'w:gz')
         except EnvironmentError as msg:
-            log.warn(str(msg))
+            LOG.warning(str(msg))
             self.user.notify_error(_('Failure writing %s') % self.filename, str(msg))
             return 0
 

gramps/plugins/export/exportxml.py

@@ -166,7 +166,7 @@ class GrampsXmlWriter(UpdateCallback):
                 else:
                     g = open(filename,"wb")
             except IOError as msg:
-                LOG.warn(str(msg))
+                LOG.warning(str(msg))
                 raise DbWriteFailure(_('Failure writing %s') % filename,
                                         str(msg))
                 return 0