[minor] Correct mph display

[NJAldwin]

I noticed the speed in the FP Camera seemed to be slightly off from what other data is showing. I traced it back to the UI here:

FirstPersonCameraContinued/UIMod/src/panels/FollowedVehicleInfoPanel.tsx

Lines 49 to 50 in a435aa8

	const toMph = (s: number) => Math.round(s * 1.26) + " mph";
	const toKmh = (s: number) => Math.round(s * 1.8) + " km/h";

It's converting the game's speed unit (m/s * 2) to km/h with the formula I'd expect (1 m/s = 3.6 km/h, so * 1.8 works), but the mph calculation is off. Per Google, it should be 1 m/s = 2.237 mph, so this should multiply by 1.11847 to get the correct mph.

Looks like the 1.26 factor has been around since mph was introduced: f3f1955

[NJAldwin]

(btw if this is incorrect and the game actually uses different units for the speed internally when using mph, that's fine -- I would want to know where the 1.26 is coming from so I can update conversions elsewhere!)