Pin matplolib as upgrade of seaborn has conflict

[Philmod]

Fix confirmed for heatmap and Learn: https://screenshot.googleplex.com/8QkKyTxyu95VPgt

http://b/308525631

[Philmod]

We can't upgrade seaborn to 0.13.0 because of a conflict:

ERROR: pip's dependency resolver does not currently take into account all the packages that are installed. This behaviour is the source of the following dependency conflicts.
ydata-profiling 4.5.1 requires numpy<1.24,>=1.16.0, but you have numpy 1.24.3 which is incompatible.
ydata-profiling 4.5.1 requires seaborn<0.13,>=0.10.1, but you have seaborn 0.13.0 which is incompatible.