title: terraform with gcp provider fails in apply due to some authentication error
body: <p>i have a simple code which creates VPC on google cloud but when i apply then it throws an error  oauth2: cannot fetch token:
  I had created a service account and assigned it editor role to project,Network,Compute Engine, service account token and service account admin. Created a key and downloaded it's json.
  I feel i might have missed something which i'm not able to figure out.</p>
  
  <p>here's my code</p>
  
  <pre><code>  credentials = file("poc-dev-terrafrom-0ea89j6c1fce.json")
    project     = "dev-terrafrom"
    region      = "us-central1"
  }
  resource "google_compute_network" "vpc_network" {
    name = "GCPvpc"
    project = "dev-terrafrom "
    auto_create_subnetworks = false
  }
  
  resource "google_compute_subnetwork" "network-with-private-secondary-ip-ranges" {
    name          = "test-subnetwork"
    ip_cidr_range = "10.0.0.0/26"
    region        = "us-central1"
    network       = google_compute_network.vpc_network.self_link
  }
  
  upon apply get below error
    Enter a value: yes
  
  google_compute_network.vpc_network: Creating...
  
  Error: Error creating Network: Post https://www.googleapis.com/compute/v1/projects/dev-terrafrom%20/global/networks?alt=json: oauth2: cannot fetch token: Post https://oauth2.googleapis.com/token: x509: certificate signed by unknown authority
  
    on vpc.tf line 1, in resource "google_compute_network" "vpc_network":
     1: resource "google_compute_network" "vpc_network" {```
  
  </code></pre>