ITensorGPU v0.2.3

Merged pull requests:

• Add CI workflows and docs (#1) (@mtfishman)
• Delete most source code and instead rely on NDTensorsCUDAExt (#3) (@mtfishman)
• Switch to ITensorMPS.jl (#7) (@mtfishman)
• Fix broken tests (#8) (@mtfishman)
• Use random_itensor and random_mps (#9) (@mtfishman)

Closed issues:

• TagBot trigger issue (#6)