fix: build failure on latest nixpkgs-unstable

[shivaraj-bh]

by updating:

• flake: nixpkgs and rust-flake
• cargo: syntect crate

resolves #494

[shivaraj-bh]

Updating rust-flake fixed the rust-src unpack phase failure

Now, I have hit the gcc-15 failure from #494

error: failed to run custom build command for `onig_sys v69.8.1`

Caused by:
  process didn't exit successfully: `/build/source/target/release/build/onig_sys-83a1b4f33be478ec/build-script-build` (exit status: 1)

[shivaraj-bh]

syntect depends on onig depends on onig-sys

updating syntect in omnix's Cargo.toml to fix the build failures of transitive dep. onig-sys

[shivaraj-bh]

nix path-info --json -S .#default changed from

[{"closureSize":140856936,"narHash":"sha256-F5vYnjdklIVT8lHE8ER48udSNMa8iy/EnsGLfGVSgNY=","narSize":16398712,"path":"/nix/store/dmyjjxghws8wabx0qpj9bh2yfg854id1-omnix-cli-1.3.1","references":["/nix/store/2qkf3pn85y4w42wwwmwf5qk9q3qb3jcw-source","/nix/store/3a40qm24lf4613583mqq3nkbwras21gk-openssl-static-x86_64-unknown-linux-musl-3.0.14-etc","/nix/store/3hpk8kjrlb8ya3gi4v6719c404j039ar-source","/nix/store/7qp5vxibp4xplkavfmdyisigk565skfx-source","/nix/store/g1pv78p6lk92hjzr7syrcihvj4rx1fnz-source","/nix/store/ivsbmc1k70j2qmrcjgxn5cvl3hcnbbf4-source","/nix/store/q0d27l8jjsva6mhwxx6lmjlgw2dmnrl8-cachix-1.7.4-bin","/nix/store/qm8q4kylp1jy68k34c2bskpamxgyc9ix-source","/nix/store/wb47j3cp8fjjgidlqlr2mhwi5zwmvsqh-source","/nix/store/wgpiafbd9rf99h9wanmbpngbgkgkh5y7-source","/nix/store/zv1922n8w830n2q1ll97hy7rb7frx9kw-source"],"registrationTime":1767622050,"signatures":["oss:P2oYyeO6DG04sWDEkRxsgfS1MvfqeW8C2uluPP3pBlg/R08xZOF7GkYqO+mNY5LazDmJqwXtMMGcdJ9sbOAhCA=="],"valid":true}]

to

{"/nix/store/1wdf8rkdnjslnfiisn60xgp3d9pj07sw-omnix-cli-0.0.1":{"ca":null,"closureSize":183248000,"deriver":"/nix/store/j68kh337pbhc0vs652mlfz7xgp1zm1l3-omnix-cli-0.0.1.drv","narHash":"sha256-cjglh0a69rFualEIH17YWrexs6xm4Q7BVvmZLxDchTM=","narSize":18724280,"references":["/nix/store/0d2m62wll0k5zb7yq9sk1qmivzmzx31d-cachix-1.9.1-bin","/nix/store/2xrhw4w7x51mmrpyrm8rs9zkz9bfzamh-source","/nix/store/3hpk8kjrlb8ya3gi4v6719c404j039ar-source","/nix/store/62lpgsspp65kdl92pjhd0xlym559ypb7-openssl-static-x86_64-unknown-linux-musl-3.6.0-etc","/nix/store/7qp5vxibp4xplkavfmdyisigk565skfx-source","/nix/store/g1pv78p6lk92hjzr7syrcihvj4rx1fnz-source","/nix/store/ivsbmc1k70j2qmrcjgxn5cvl3hcnbbf4-source","/nix/store/qm8q4kylp1jy68k34c2bskpamxgyc9ix-source","/nix/store/wb47j3cp8fjjgidlqlr2mhwi5zwmvsqh-source","/nix/store/wgpiafbd9rf99h9wanmbpngbgkgkh5y7-source","/nix/store/zv1922n8w830n2q1ll97hy7rb7frx9kw-source"],"registrationTime":1767622022,"signatures":[],"ultimate":true}}

Hence, the jq script to parse the closureSize had to be modified, see d408183

[shivaraj-bh]

packages.default builds successfully on x86_64-darwin