chore(ci): update release workflow to use nix and just for releases

Replaced `earthly` with `nix` and `just` in the release workflow.
This improves build consistency and leverages flakes for reproducibility.

.github/workflows/releases.yml

@@ -29,15 +29,8 @@ jobs:
           username: "NumaryBot"
           password: ${{ secrets.NUMARY_GITHUB_TOKEN }}
       - run: >
-          earthly
-          --no-output
-          --allow-privileged
-          --secret SPEAKEASY_API_KEY=$SPEAKEASY_API_KEY
-          --secret GITHUB_TOKEN=$GITHUB_TOKEN
-          --secret FURY_TOKEN=$FURY_TOKEN
-          --secret GORELEASER_KEY=$GORELEASER_KEY
-          ${{ contains(github.event.pull_request.labels.*.name, 'no-cache') && '--no-cache' || '' }}
-          +release --mode=release
+          /nix/var/nix/profiles/default/bin/nix --extra-experimental-features "nix-command" --extra-experimental-features "flakes" 
+          develop --impure --command just release
         env:
           GITHUB_TOKEN: ${{ secrets.NUMARY_GITHUB_TOKEN }}
           SPEAKEASY_API_KEY: ${{ secrets.SPEAKEASY_API_KEY }}