No module named 'simplejson' when starting rustfava-server

[ayaye]

Description

I've upgraded from 1.30.13 to 1.31.0 and see the following stack trace when starting rustfava-server:

Traceback (most recent call last):
  File "cli.py", line 191, in <module>
  File "click/core.py", line 1569, in __call__
  File "click/core.py", line 1490, in main
  File "click/core.py", line 1353, in invoke
  File "click/core.py", line 907, in invoke
  File "cli.py", line 129, in main
  File "pyimod02_importers.py", line 457, in exec_module
  File "rustfava/application.py", line 47, in <module>
  File "pyimod02_importers.py", line 457, in exec_module
  File "rustfava/_ctx_globals_class.py", line 10, in <module>
  File "pyimod02_importers.py", line 457, in exec_module
  File "rustfava/core/__init__.py", line 30, in <module>
  File "pyimod02_importers.py", line 457, in exec_module
  File "rustfava/core/charts.py", line 16, in <module>
ModuleNotFoundError: No module named 'simplejson'

Probably is is because import change from 'json' to 'simplejson' in charts.py, line 16

Steps to Reproduce

1. Install rustfava_1.31.0_amd64.deb
2. Start rustfava-server
3. See ModuleNotFoundError: No module named 'simplejson'

Rustfava Version

1.31.0

Python Version

3.13.11

Operating System

Linux

Additional Context

No response