Closes #27630

PR summary

Issue #27630 highlighted how passing a size value inside fontdict was being ignored within figure.suptitle. This was happening because the default kwargs sent to Text were being updated with the defaults last (i.e. highest priority). Switching the order of the dictionary update fixes this, giving highest priority to arguments specified in fontdict by the user.

Test code by @boffi:

import matplotlib.pyplot as plt

fig = plt.figure(figsize=(8, 3), layout='constrained')
f0, f1 = fig.subfigures(1, 2)
f0.suptitle('xxxXXX', fontdict=dict(family='Candara', size=30))
f0.add_subplot().set_title('xxxXXX', fontdict=dict(family='Candara', size=20))
f1.suptitle('xxxXXX', size=30, fontdict=dict(family='Candara'))
f1.add_subplot().set_title('xxxXXX', size=20, fontdict=dict(family='Candara'))
plt.show()

Broken behavior:

Fixed behavior:

PR checklist

• "closes #0000" is in the body of the PR description to link the related issue
• new and changed code is tested
• N/A Plotting related features are demonstrated in an example
• N/A New Features and API Changes are noted with a directive and release note
• N/A Documentation complies with general and docstring guidelines

Note: This is my first PR. Please let me know if I messed up anything here.