Fix MacOS builds on Big Sur+

[cidkidnix]

GHC 8.6.5 needs a patch to properly load frameworks which is what the r-p bump does

We don't set the NIX_PATH in the nix-shell command env which ends up making nix-shell fall back to system-bash which we shouldn't rely on existing (or working properly). The haskell portion of this sets NIX_PATH to nixpkgs to properly pull bash from nixpkgs

depends on https://github.com/reflex-frp/reflex-platform/pull/810

I have:

• [ ] Based work on latest develop branch
• [ ] Followed the contribution guide
• [ ] Looked for lint in my changes with hlint . (lint found code you did not write can be left alone)
• [ ] Run the test suite: $(nix-build -A selftest --no-out-link)
• [ ] Updated the changelog
• [ ] (Optional) Run CI tests locally: nix-build release.nix -A build.x86_64-linux --no-out-link (or x86_64-darwin on macOS)