fix flaky tests

[kanarus]

• [x] ohkami/response/_test.rs
  • ~~1 second difference of Date → calculate current timestamps by each~~
  • ~~but it only decrease the possibility, not prevent difference~~
  • → clone res's Date and use it in $expected
• [ ] samples/test.sh
  • Connection Refused in petstore's npm run main
• [x] ohkami/x_lambda.rs
  • ~~timing conflict around static ROUTER~~ → unify tests around Service into single one