Circadian Lighting [Custom Component]

I can’t seem to get this going because of a missing dependency, any idea how to resolve this? I have restarted many times, not sure why it’s throwing an error.

2018-08-08 05:51:59 ERROR (MainThread) [homeassistant.loader] Error loading custom_components.switch.circadian_lighting. Make sure all dependencies are installed
Traceback (most recent call last):
  File "/usr/src/app/homeassistant/loader.py", line 94, in get_component
    module = importlib.import_module(path)
  File "/usr/local/lib/python3.6/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 994, in _gcd_import
  File "<frozen importlib._bootstrap>", line 971, in _find_and_load
  File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 678, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/config/custom_components/switch/circadian_lighting.py", line 9, in <module>
    from custom_components.circadian_lighting import DOMAIN, CIRCADIAN_LIGHTING_UPDATE_TOPIC, DATA_CIRCADIAN_LIGHTING
  File "/config/custom_components/circadian_lighting.py", line 50, in <module>
    from timezonefinder import TimezoneFinder
ModuleNotFoundError: No module named 'timezonefinder'