Extend the README steps for building the standalone executable (pip install numpy<2.0)

[js485]

Provide environment information

Python 3.9.13
labelme 5.6.1

What OS are you using?

Microsoft Windows

Describe the Bug

Hi,

for building the standalone executable, it seems like numpy versions >= 2.0 yield errors.
pip-installing numpy<2.0 fixed the problem.
Maybe, you can add that to README.md.

# Build the standalone executable
pip install .
pip install 'matplotlib<3.3'
pip install numpy<2.0
pip install pyinstaller
pyinstaller labelme.spec
dist/labelme --version

Expected Behavior

Following the steps for building the standalone executable as described in the README should not yield errors.

To Reproduce

I created a fresh python 3.9.13 environment (as proposed in the README, though I used python -m venv instead of conda) and then followed the process for building the standalone executable as described in the README:

# Build the standalone executable
pip install .
pip install 'matplotlib<3.3'
pip install pyinstaller
pyinstaller labelme.spec

The last command runs into an error resulting from numpy.