Recreate credentials for given user in PG Cluster.

curl --request POST \
  --url https://api.gcore.com/cloud/v1/dbaas/postgres/clusters/{project_id}/{region_id}/{cluster_name}/users/{username}/credentials \
  --header 'APIKey: <api-key>'

{
  "password": "<PASSWORD>",
  "username": "myuser"
}