Memory leaks can be caused every time an animation is created

[headjoe3]

I discovered this issue while helping someone else with my Roblox-TS port of roact-animate

Basically, this line causes a connection that never gets disconnected

If AnimatedValues persist while new Animations are created (see the basic example where an infinite loop generates animations), these connections will remain in memory, and can cause some bugs after a few animations have been created.

I already created a fix for this on my TS module, and ported it to the vanilla version to the best of my ability (see #12 )