Negative number flag values are set to strings after updating

[rolodato]

How are you running Flagsmith

• [ ] Self Hosted with Docker
• [ ] Self Hosted with Kubernetes
• [X] SaaS at flagsmith.com
• [ ] Some other way (add details in description below)

Describe the bug

See steps below.

Steps To Reproduce

1. Create a new feature with a value of -1. Its value will be correctly saved as an integer
2. Update the feature; erase and type in -1 again, and save
3. The value will be incorrectly saved as the string "-1"

Expected behavior

Valid integers should always be saved as integers.

Screenshots

https://github.com/Flagsmith/flagsmith/assets/829698/86d39885-f314-4c6f-b0ba-d4aee99494da