r/aws_ses_domain_identity_verification: compare enum types

```console
% make testacc PKG=ses TESTS=TestAccSESDomainIdentityVerification_
make: Verifying source code with gofmt...
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go1.22.5 test ./internal/service/ses/... -v -count 1 -parallel 20 -run='TestAccSESDomainIdentityVerification_'  -timeout 360m
=== RUN   TestAccSESDomainIdentityVerification_basic
    domain_identity_verification_test.go:27: Environment variable SES_DOMAIN_IDENTITY_ROOT_DOMAIN is not set. For DNS verification requests, this domain must be publicly accessible and configurable via Route53 during the testing.
--- SKIP: TestAccSESDomainIdentityVerification_basic (0.00s)
=== RUN   TestAccSESDomainIdentityVerification_timeout
=== PAUSE TestAccSESDomainIdentityVerification_timeout
=== RUN   TestAccSESDomainIdentityVerification_nonexistent
=== PAUSE TestAccSESDomainIdentityVerification_nonexistent
=== CONT  TestAccSESDomainIdentityVerification_timeout
=== CONT  TestAccSESDomainIdentityVerification_nonexistent
--- PASS: TestAccSESDomainIdentityVerification_nonexistent (4.52s)
--- PASS: TestAccSESDomainIdentityVerification_timeout (11.75s)
PASS
ok      github.com/hashicorp/terraform-provider-aws/internal/service/ses        16.412s
```

internal/service/ses/domain_identity_verification.go

@@ -82,7 +82,7 @@ func resourceDomainIdentityVerificationCreate(ctx context.Context, d *schema.Res
 			return retry.NonRetryableError(fmt.Errorf("SES Domain Identity %s not found in AWS", domainName))
 		}
 
-		if string(att.VerificationStatus) != string(awstypes.VerificationStatusSuccess) {
+		if att.VerificationStatus != awstypes.VerificationStatusSuccess {
 			return retry.RetryableError(fmt.Errorf("Expected domain verification Success, but was in state %s", string(att.VerificationStatus)))
 		}
 
@@ -92,7 +92,7 @@ func resourceDomainIdentityVerificationCreate(ctx context.Context, d *schema.Res
 		var att *awstypes.IdentityVerificationAttributes
 		att, err = getIdentityVerificationAttributes(ctx, conn, domainName)
 
-		if att != nil && string(att.VerificationStatus) != string(awstypes.VerificationStatusSuccess) {
+		if att != nil && att.VerificationStatus != awstypes.VerificationStatusSuccess {
 			return sdkdiag.AppendErrorf(diags, "Expected domain verification Success, but was in state %s", string(att.VerificationStatus))
 		}
 	}
@@ -123,7 +123,7 @@ func resourceDomainIdentityVerificationRead(ctx context.Context, d *schema.Resou
 		return diags
 	}
 
-	if string(att.VerificationStatus) != string(awstypes.VerificationStatusSuccess) {
+	if att.VerificationStatus != awstypes.VerificationStatusSuccess {
 		log.Printf("[WARN] Expected domain verification Success, but was %s, tainting verification", string(att.VerificationStatus))
 		d.SetId("")
 		return diags