Fix example workflow errors in triggers

[vemel]

I have noticed that !master branch in example workflow triggers produces an invalid YAML

[github-actions]

Terraform plan for pull_request_target

Plan: 1 to add, 0 to change, 0 to destroy. Changes to Outputs.

An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
  + create

Terraform will perform the following actions:

  # random_string.my_string will be created
  + resource "random_string" "my_string" {
      + id          = (known after apply)
      + length      = 11
      + lower       = true
      + min_lower   = 0
      + min_numeric = 0
      + min_special = 0
      + min_upper   = 0
      + number      = true
      + result      = (known after apply)
      + special     = true
      + upper       = true
    }

Plan: 1 to add, 0 to change, 0 to destroy.

Changes to Outputs:
  + output_string = "the_string"

Plan applied in pull_request_target test #8

[dflook]

Thanks @vemel, you are quite right.