fix: nix devshell using the right pkg name, s/gocode/gocode-gomod

       … while evaluating 'strict' to select 'drvPath' on it
         at /builtin/derivation.nix:1:552:
       … while calling the 'derivationStrict' builtin
         at /builtin/derivation.nix:1:208:
       (stack trace truncated; use '--show-trace' to show the full trace)

       error: attribute 'gocode' missing
       at /nix/store/7r2yz90q994vr66n8gy7r9wwjvd6pzif-source/flake.nix:270:15:
          269|               pkgs.go-outline
          270|               pkgs.gocode
             |               ^
          271|               pkgs.gopkgs
       Did you mean one of gecode, avocode, goose, lolcode or qrcode?

Author: yvan-sraka

flake.nix

@@ -251,7 +251,7 @@
               pkgs.gopls
               pkgs.gotools
               pkgs.go-outline
-              pkgs.gocode
+              pkgs.gocode-gomod
               pkgs.gopkgs
               pkgs.godef
               pkgs.golint