fix: overlapping CGO_ENABLED = 0

When ess is a flake input to other devenv projects, it fails with the following:

> error: The `env` attribute set cannot contain any attributes passed to derivation. The following attributes are overlapping:
>   - CGO_ENABLED: in `env`: 0; in derivation arguments: 1

Author: acaloiaro

.gitignore

@@ -2,3 +2,4 @@
 .pre-commit-config.yaml
 result/
 /ess
+.devenv/

flake.nix

@@ -66,12 +66,6 @@
                 go-tools
                 gopls
               ]);
-
-            shellHook =
-              # bash
-              ''
-                export CGO_ENABLED=0
-              '';
           };
         };
       }