[typescript(experimental)] fix for Deno

Created by: chibat

Code generated with v5.4.0 does not work with typescript deno.

$ wget https://repo1.maven.org/maven2/org/openapitools/openapi-generator-cli/5.4.0/openapi-generator-cli-5.4.0.jar -O openapi-generator-cli.jar
$ java -jar openapi-generator-cli.jar generate -i https://petstore.swagger.io/v2/swagger.json -g typescript --additional-properties=platform=deno -o generated-src
$ deno
Deno 1.19.3
exit using ctrl+d or close()
> import * as petstore from "./generated-src/index.ts";

const configuration = petstore.createConfiguration();
const petApi = new petstore.PetApi(configuration);
const pets = await petApi.findPetsByStatus(["available"]); 
console.log(pets.slice(0, 5));
Uncaught TypeError: Module not found "file:///home/chiba/data/work/oag/generated-src/auth/auth".
    at file:///home/chiba/data/work/oag/generated-src/apis/UserApi.ts:8:38
    at async <anonymous>:2:18

I fixed it.

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