fix(hz): service gen dir failed

[FGYFFFF]

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fix

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修复 hz 在 "service_gen_dir" 注解下，生成的 router.go 缺少 import 的问题

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en: fix a missing import in router.go generated by hz under the "service_gen_dir" annotation. zh(optional): 修复 hz 在 "service_gen_dir" 注解下，生成的 router.go 缺少 import 的问题

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