fix: dont compute so many fibonacci numbers

[armcknight]

I tried running the demo on an iPhone 14, and it crashes with an arithmetic overflow when computing around the 650th fibonacci number. It is probably due to running an optimized build? Doubt it's due to the different device, since both my phone and mac are running an apple silicon arm chip.

Just dialing down the limit from 4000 to 500 fib numbers fixed it.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 39.526%. Comparing base (75800b2) to head (598f80c).

Additional details and impacted files

@@              Coverage Diff              @@
##            master       #90       +/-   ##
=============================================
+ Coverage   37.655%   39.526%   +1.870%     
=============================================
  Files           10        10               
  Lines          802       802               
  Branches       255       255               
=============================================
+ Hits           302       317       +15     
+ Misses         492       476       -16     
- Partials         8         9        +1     

Files	Coverage Δ
EmpowerPlant/EmpowerPlantViewController.swift	61.172% <0.000%> (ø)

... and 1 file with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 75800b2...598f80c. Read the comment docs.