remove optional mpl import

MarcoGorelli · MarcoGorelli · commit 2ceaa13ee685 · 2020-11-26T11:13:14.000Z
diff --git a/pymc3/plots/posteriorplot.py b/pymc3/plots/posteriorplot.py
@@ -19,7 +19,6 @@
 
 from pymc3.backends.base import MultiTrace
 
-
 if TYPE_CHECKING:  # pragma: nocover
     from arviz.data.inference_data import InferenceData
 
