Fix compile errors

The `@pulumi/policy` library was updated to support remediations, but this repo hasn't been updated since then. This commit fixes some compile errors due to the changes there.

Note: This points out that we're missing a daily cron in this repro to catch these things sooner.

src/enforcementLevel.ts

@@ -28,6 +28,7 @@ export function isEnforcementLevel(o: any): o is EnforcementLevel {
             case "advisory":
             case "disabled":
             case "mandatory":
+            case "remediate":
                 return true;
             default:
                 return exhaustiveFalse(enforcementLevel);

src/tests/util.ts

@@ -103,6 +103,9 @@ async function runResourcePolicy(resPolicy: policy.ResourceValidationPolicy, arg
         ? resPolicy.validateResource
         : [resPolicy.validateResource];
     for (const validation of validations) {
+        if (!validation) {
+            throw Error("validateResource must be a function or array of functions.");
+        }
         await Promise.resolve(validation(args, report));
     }
     return violations;