Failing `TestPlan_WithPolicyUnknown` test

[SarahFrench]

This failure came up on main branch:

Run go test -race ./internal/terraform ./internal/command ./internal/states ./internal/promising ./internal/stacks/...
go: downloading github.com/go-test/deep v1.0.3
ok  	github.com/hashicorp/terraform/internal/terraform	44.266s
--- FAIL: TestPlan_WithPolicyUnknown (0.02s)
    plan_policy_test.go:457: unexpected output:
        data.test_data_source.a: Reading...
        data.test_data_source.a: Read complete after 1s [id=zzzzz]
        
        Warning: policy with unknowns
        
          on policy_file.tfpolicy.hcl line 1:
           1: 		resource_policy "resource_type" "policy_name" {
           2: 		  enforce_attrs {
           3: 		    key = attr.value == "foo"
           4: 		  }
           5: 		}
           6: 	
        
          while evaluating policy for main.tf line 1:
           1: resource "test_instance" "foo" {
        
        
        Terraform used the selected providers to generate the following execution
        plan. Resource actions are indicated with the following symbols:
          + create
        
        Terraform will perform the following actions:
        
          # test_instance.foo will be created
          + resource "test_instance" "foo" {
              + ami = "bar"
        
              + network_interface {
                  + description  = "Main network interface"
                  + device_index = "0"
                }
            }
        
        Plan: 1 to add, 0 to change, 0 to destroy.
        
        ─────────────────────────────────────────────────────────────────────────────
        
        Note: You didn't use the -out option to save this plan, so Terraform can't
        guarantee to take exactly these actions if you run "terraform apply" now.
        . 
        Diff:   strings.Join({
          	"data.test_data_source.a: Reading...\ndata.test_data_source.a: Rea",
          	"d complete after ",
        - 	"0",
        + 	"1",
          	"s [id=zzzzz]\n\nWarning: policy with unknowns\n\n  on policy_file.tf",
          	"policy.hcl line 1:\n   1: \t\tresource_policy \"resource_type\" \"poli",
          	... // 1041 identical bytes
          }, "")
FAIL