Fix config error with emcpy_horizontal_line.py Ref (#204)

Fix horizontal line config error. Use the correct config information in
the plot object.

I ran into this issue last week but assumed it had to be an install
issue, not a simple coding error. I'm not sure how/why this worked as
long as it did. Maybe the unrecognized variable in the plot object is ok
in python3 environments that aren't on Rocky8?

Close #203

src/eva/plotting/batch/emcpy/diagnostics/emcpy_horizontal_line.py

@@ -43,7 +43,7 @@ def configure_plot(self):
         delvars = ['type', 'schema']
         for d in delvars:
             new_config.pop(d, None)
-        self.plotobj = update_object(self.plotobj, self.config, self.logger)
+        self.plotobj = update_object(self.plotobj, new_config, self.logger)
 
         return self.plotobj