Update shell.nix (fixes Mac)

[nshalman]

Description

Update shell.nix

Why is this needed

nix-shell was broken on Mac:

tink $ nix-shell
this derivation will be built:
  /nix/store/4qb68dq0paaqrkiv7c4m1kikkxvk4sk3-nixfmt-0.4.0.drv
building '/nix/store/4qb68dq0paaqrkiv7c4m1kikkxvk4sk3-nixfmt-0.4.0.drv'...
setupCompilerEnvironmentPhase
Build with /nix/store/88242sfskrw2mxv2pr4608nwccpw5q41-ghc-8.8.4.
unpacking sources
unpacking source archive /nix/store/l50bqw5ac3vzm9fmqijkxga7hjcnvd5p-nixfmt-0.4.0.tar.gz
source root is nixfmt-0.4.0
setting SOURCE_DATE_EPOCH to timestamp 1000000000 of file nixfmt-0.4.0/src/Nixfmt/Util.hs
patching sources
Replace Cabal file with edited version from mirror://hackage/nixfmt-0.4.0/revision/1.cabal.
Run jailbreak-cabal to lift version restrictions on build inputs.
compileBuildDriverPhase
setupCompileFlags: -package-db=/private/tmp/nix-build-nixfmt-0.4.0.drv-0/setup-package.conf.d -j12 -threaded -rtsopts
[1 of 1] Compiling Main             ( /nix/store/4mdp8nhyfddh7bllbi7xszz7k9955n79-Setup.hs, /private/tmp/nix-build-nixfmt-0.4.0.drv-0/Main.o )
Linking Setup ...
ld: file not found: /usr/lib/system/libcache.dylib for architecture x86_64
clang-7: error: linker command failed with exit code 1 (use -v to see invocation)
`cc' failed in phase `Linker'. (Exit code: 1)
error: builder for '/nix/store/4qb68dq0paaqrkiv7c4m1kikkxvk4sk3-nixfmt-0.4.0.drv' failed with exit code 1

How Has This Been Tested?

• CI
• nix-shell on both Mac and Linux

How are existing users impacted? What migration steps/scripts do we need?

N/A

Checklist:

I have:

• updated the documentation and/or roadmap (if required)
• added unit or e2e tests
• provided instructions on how to upgrade

[codecov]

Codecov Report

Merging #562 (9f73ef7) into main (058a1c9) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #562   +/-   ##
=======================================
  Coverage   34.76%   34.76%           
=======================================
  Files          44       44           
  Lines        3348     3348           
=======================================
  Hits         1164     1164           
  Misses       2085     2085           
  Partials       99       99           

---

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[mmlb]

Can you provide some more detail wrt what was broken please (in the commit message). I wonder if maybe applicable to other repos too.

[nshalman]

Can you provide some more detail wrt what was broken please (in the commit message). I wonder if maybe applicable to other repos too.

Updated in the description.

[jacobweinstock]

/lgtm