Update update-trinity

[Grazfather]

If python points to python3, then building will fail.

Fixed version is here:

https://gist.githubusercontent.com/Grazfather/91e1ea3c3b51be844552263ce0f0d538/raw/c5607a51047b4dc01bf1f3fd443e8cd6318056c6/install-trinity.sh

[Grazfather]

Could also be sped up by using git clone --depth 1
Also it calls ldconfig to update the library search paths, and issue I had in some docker images.

[hugsy]

453fdcb