Executable size using module matplotlib 3.4.x

[interflexo]

Executable size of some project using module matplotlib until 3.3.4 is about 40Mb.
Using module matplotlib 3.4.0 or 3.4.1 the executable size jumps to 400Mb with no other code changes. App always works as expected.

• Output of pyinstaller --version: 4.2
• Version of Python: 3.8
• Platform: Windows 10
• Did you also try this on another platform? No

[rokm]

Matplotlib 3.4.x is not supported by Pyinstaller 4.2 (see #5567); instead you'll have to use develop branch which contains the fix (#5568).