fix: remove whitespace from netboxbackup chart directory

There is an accidental whitespace at the end of the netboxbackup chart subdirectory which currently breaks the build process. I am not sure why the ci is not complaining about this, but at least building the charts locally does not work for me due to this error:

2026-02-16 13:17:09,680    INFO  yaook.helm_builder.cli  Creating Helm-Chart netboxbackup
Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File "/home/felix/yaook/operator/yaook/helm_builder/__main__.py", line 23, in <module>
    sys.exit(yaook.helm_builder.cli.main() or 0)
             ~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/home/felix/yaook/operator/yaook/helm_builder/cli.py", line 297, in main
    build_charts(args.charts, args.upload is not None)
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/felix/yaook/operator/yaook/helm_builder/cli.py", line 219, in build_charts
    file_info = build_chart(
        logger,
    ...<2 lines>...
        image_versions,
    )
  File "/home/felix/yaook/operator/yaook/helm_builder/cli.py", line 150, in build_chart
    build_cue_templates(logger, path)
    ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^
  File "/home/felix/yaook/operator/yaook/helm_builder/cli.py", line 82, in build_cue_templates
    for entry in outdir.iterdir():
                 ~~~~~~~~~~~~~~^^
  File "/usr/lib64/python3.14/pathlib/__init__.py", line 836, in iterdir
    with os.scandir(root_dir) as scandir_it:
         ~~~~~~~~~~^^^^^^^^^^
FileNotFoundError: [Errno 2] No such file or directory: '/home/felix/yaook/operator/yaook/helm_builder/Charts/netboxbackup/templates'
make: *** [GNUmakefile:34: yaook/helm_builder/Charts/netboxbackup/values.yaml] Error 1