Cannot Purchase the Naturalist Faith Unit

**Describe the bug**
After researching conservation and meeting the requirements to create a national park, the unit still doesn't appear to be able to be purchased in the production menu.

**To Reproduce**
Steps to reproduce the behavior:
1. Unlock the Conservation Civic (Modern Era, I believe)
2. Click on the city production menu
3. Scroll down to the units
4. No naturalist available to purchase with faith (other faith units relating to religion are there, however)

**Expected behavior**
To be able to purchase a naturalist with faith.

**General informations**
- OS: Windows 10
- Version: 1909
- Expansion: All
- A few other mods that shouldn't affect this specific issue

**Save game and logs**
[FREDERICK BARBAROSSA 369 1716 AD.zip](https://github.com/Azurency/CQUI_Community-Edition/files/4562675/FREDERICK.BARBAROSSA.369.1716.AD.zip)
[Civ.VI.Logs.zip](https://github.com/Azurency/CQUI_Community-Edition/files/4562678/Civ.VI.Logs.zip)

Load the linked save game and reproduce the issue from the city production menu after unlocking the Conservation Civic. Trace the production-menu handling for the Naturalist and compare it with the other faith-purchasable units, using the supplied logs if needed. Done means the Naturalist appears in the menu and can be purchased with faith under the stated requirements.

Written by the indexing model from the issue text.