[client] Solve CORS bug when fetching with GET method

When making a GET request with the httpClient, the header
Content-Type: application-json was provided (which makes no sense).
4 jobs for topic/default/fetching-bug in 3 minutes and 27 seconds (queued for 26 seconds)
Status Job ID Name Coverage
  Deps
passed Deps #29366

00:02:01

 
  Test
passed CanBuild #29369

00:01:25

passed Format #29368

00:00:58

passed Lint #29367

00:01:05