Describe the bug
The plot_bundt method fails with the following traceback:

Traceback (most recent call last):
  Cell 
marimo://SDT_on_PVDRDB_SPWR_sites.py#cell=cell-9

, line 1, in <module>
    dh.plot_bundt()
    ~~~~~~~~~~~~~^^
  File "/Users/bmeyers/github/solar-data-tools/solardatatools/data_handler.py", line 2513, in plot_bundt
    doy[doy > 59] -= 1  # adjust for removed Feb 29
    ~~~^^^^^^^^^^
ValueError: assignment destination is read-only

To Reproduce
Steps to reproduce the behavior:

1. Load any data and run initial pipeline
2. run plot_bundt method

Expected behavior
We expect to generate a Bundt plot, not an exception

Environment (please complete the following information about your working environment):

• OS: Mac OS
• Python version: 3.13
• Solar Data Tools version: 2.1.1
• numpy: 2.4.2
• pandas: 3.0.0