Mandrake v1.2.3: GPU compile

Fixes a flag exporting the GPU code, used on conda

What's Changed

• Update the citation and logo by @johnlees in #32
• Vendor boost lib by @richfitz in #33
• Allow one to set CUDAARCHS. by @ccoulombe in #36
• Simplify and fix CI by @johnlees in #38
• Add readthedocs config file by @johnlees in #42
• Add GPU_AVAILABLE macro to makefile for conda by @absternator in #45

New Contributors

• @richfitz made their first contribution in #33
• @ccoulombe made their first contribution in #36
• @absternator made their first contribution in #45

Full Changelog: v1.2.2...v1.2.3