Fix datatime issue when inventory key contains a date

[ademariag]

Fixes issue with datatime in inventory keys

./kapitan searchvar gen_google_container_cluster
Traceback (most recent call last):
  File "/opt/venv/bin/kapitan", line 8, in <module>
    sys.exit(main())
             ^^^^^^
  File "/opt/venv/lib/python3.11/site-packages/kapitan/cli.py", line 645, in main
    args.func(args)
  File "/opt/venv/lib/python3.11/site-packages/kapitan/utils.py", line 330, in searchvar
    value = deep_get(data, keys)
            ^^^^^^^^^^^^^^^^^^^^
  File "/opt/venv/lib/python3.11/site-packages/kapitan/utils.py", line 81, in lru_decorator
    _args = tuple([json.dumps(arg, sort_keys=True) if type(arg) in (list, dict) else arg for arg in args])
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/venv/lib/python3.11/site-packages/kapitan/utils.py", line 81, in <listcomp>
    _args = tuple([json.dumps(arg, sort_keys=True) if type(arg) in (list, dict) else arg for arg in args])
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/json/__init__.py", line 238, in dumps
    **kw).encode(obj)
          ^^^^^^^^^^^
  File "/usr/local/lib/python3.11/json/encoder.py", line 200, in encode
    chunks = self.iterencode(o, _one_shot=True)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/json/encoder.py", line 258, in iterencode
    return _iterencode(o, 0)

Proposed Changes

Docs and Tests

• Tests added
• Updated documentation