Fix moss functional test plots when not called alone.

Author: samsrabin

testing/functional_testing/moss/moss_test.py

@@ -38,6 +38,7 @@ def plot_output(self, run_dir: str, save_figs: bool, plot_dir: str):
             plot_dir (str): plot directory to save the figures to
         """
         print("Making plots")
+        plt.close("all")
 
         # read in moss data
         moss_dat = xr.open_dataset(os.path.join(run_dir, self.out_file))