#419 update types to mark Rule.conditions as readonly

Author: emilefokkemanavara

types/index.d.ts

@@ -174,7 +174,7 @@ export interface RuleResult {
 export class Rule implements RuleProperties {
   constructor(ruleProps: RuleProperties | string);
   name: string;
-  conditions: TopLevelCondition;
+  readonly conditions: TopLevelCondition;
   /**
    * @deprecated Use {@link Rule.event} instead.
    */