Fix typo

Author: zaxtax

pymc/backends/arviz.py

@@ -660,7 +660,7 @@ def apply_function_over_dataset(
     indices = range(n_pts)
 
     with Progress(console=Console(theme=progressbar_theme)) as progress:
-        task = progress.add_task("Computinng ...", total=n_pts, visible=progressbar)
+        task = progress.add_task("Computing ...", total=n_pts, visible=progressbar)
         for idx in indices:
             out = fn(posterior_pts[idx])
             fn.f.trust_input = True  # If we arrive here the dtypes are valid