trailing new line in pvgis.py

Author: mikofski

pvlib/iotools/pvgis.py

@@ -256,4 +256,4 @@ def read_pvgis_tmy(filename, outputformat='csv'):
     err_msg = (
         "output format '{:s}' was unknown, must be either 'epw', 'json', 'csv'"
         ", or 'basic'").format(outputformat)
-    raise ValueError(err_msg)
+    raise ValueError(err_msg)