fix(ci): remove unsued stuff

Author: fumiama

.github/workflows/ci.yml

@@ -36,9 +36,6 @@ jobs:
       - name: Build all packages
         run: go build ./...
 
-      - name: Build cmd/gen
-        run: go build ./cmd/gen
-
 
   run-test:
     name: Run Test (${{ matrix.name }})