This updates the Matplotlib version to avoid segmentation faults on Macs running Big Sur. Fixes #309

Author: briangow

requirements.txt

@@ -4,7 +4,7 @@ cycler==0.10.0
 idna==2.9
 joblib==0.14.1
 kiwisolver==1.2.0
-matplotlib==3.2.1
+matplotlib==3.3.4
 nose==1.3.7
 numpy==1.18.5
 pandas==1.0.3