fix(rust-analyzer): use pname in call to buildVscodeExtension

[dustypomerleau]

Thanks for all your hard work on Fenix.

rust-analyzer builds broke for me shortly after NixOS/nixpkgs#354740 was merged.

 … from call site
         at /nix/store/bd5j75vv19g3q0ijgi4plvfwsb95648d-source/default.nix:190:5:
          189|     in
          190|     pkgs.vscode-utils.buildVscodeExtension {
             |     ^
          191|       name = "rust-analyzer-${rust-analyzer-rev}";

       error: function 'buildVscodeExtension' called without required argument 'pname'
       at /nix/store/sp3c1kqpv8lnzi9njdly8ig00gg9c3p8-source/pkgs/applications/editors/vscode/extensions/vscode-utils.nix:13:5:
           12|   buildVscodeExtension =
           13|     a@{
             |     ^
           14|       pname,

This PR works for me locally by passing pname instead of name. Please let me know if anything else needs to be done.

 - system: `"aarch64-darwin"`
 - host os: `Darwin 24.1.0, macOS 15.1.1`
 - multi-user?: `yes`
 - sandbox: `no`
 - version: `nix-env (Lix, like Nix) 2.91.1

[dustypomerleau]

Ah, sorry, it looks like this is a duplicate of #180. But in 180 the additional interpolation ${rust-analyzer-rev} has been removed—I assume it should be left in place? Happy for this to be closed if 180 is being merged.

[SuperSandro2000]

Leaving the rev here is definitely wrong as it will be duplicated in the final name.

[dustypomerleau]

I see. I'll close this, in any event, as it appears #184 is passing CI.