fix(release): remove before hook that fails in CI

GoReleaser hooks execute commands directly without a shell, so `cd`
(a shell builtin) fails. The hook is unnecessary since go.mod should
already be tidy.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.goreleaser.yml

@@ -2,10 +2,6 @@ version: 2
 
 project_name: multica
 
-before:
-  hooks:
-    - cd server && go mod tidy
-
 builds:
   - id: multica
     main: ./cmd/multica