aws/provider: redshift cluster exercise invalid password char path (#12359)

* aws/provider: redshift cluster exercise invalid password char path

* we need the password to be valid except for the one problem character

builtin/providers/aws/resource_aws_redshift_cluster_test.go

@@ -566,6 +566,10 @@ func TestResourceAWSRedshiftClusterMasterPasswordValidation(t *testing.T) {
 			Value:    "1Testing",
 			ErrCount: 0,
 		},
+		{
+			Value:    "1Testing@",
+			ErrCount: 1,
+		},
 	}
 
 	for _, tc := range cases {