fix: fix protoc-gen-openapiv2/options import issue

buf.gen.yaml

@@ -5,6 +5,7 @@ managed:
     default: github.com/instill-ai/protogen-go
     except:
       - buf.build/googleapis/googleapis
+      - buf.build/grpc-ecosystem/grpc-gateway
 plugins:
   - remote: buf.build/protocolbuffers/plugins/python:v3.19.3-1
     out: gen/python
@@ -25,11 +26,11 @@ plugins:
       - paths=source_relative
       - generate_unbound_methods=true
   - remote: buf.build/grpc-ecosystem/plugins/openapiv2:v2.10.0-1
-    out: openapiv2
+    out: gen/openapiv2
     opt:
       - output_format=yaml
       - json_names_for_fields=false
-      - allow_merge=true,merge_file_name=openapiv2
+      - allow_merge=true,merge_file_name=gen/openapiv2
       - version=true
   - remote: buf.build/sawadashota/plugins/protoc-gen-doc:v1.5.0
     out: gen/grpc-doc