test: enable typescript-axios integration test (#8163)

* test: enable typescript-axios integration test

* chore: update old dep & devDep

* refactor: use axios installed in test target

* chore(travisCI): update node version from v8.12.0 to v12.20.0

Author: gasugesu

.travis.yml

@@ -68,6 +68,8 @@ before_install:
   - curl https://sh.rustup.rs -sSf | sh -s -- -y -v
   # required when sudo: required for the Ruby petstore tests
   - gem install bundler
+  - nvm install 12.20.0
+  - nvm use 12.20.0
   - npm install -g typescript
   - npm install -g npm
   - npm config set registry http://registry.npmjs.org/

pom.xml

@@ -1221,8 +1221,7 @@
                 <module>samples/client/petstore/typescript-fetch/builds/es6-target</module>
                 <module>samples/client/petstore/typescript-fetch/builds/with-npm-version</module>
                 <module>samples/client/petstore/typescript-fetch/tests/default</module>
-                <!-- comment out due to CI failure, e.g. https://travis-ci.org/OpenAPITools/openapi-generator/builds/574865730
-                <module>samples/client/petstore/typescript-axios/tests/default</module>-->
+                <module>samples/client/petstore/typescript-axios/tests/default</module>
                 <module>samples/client/petstore/typescript-node/npm</module>
                 <module>samples/client/petstore/typescript-rxjs/builds/with-npm-version</module>
                 <!-- comment out due to error `npm run build`