chore: fix unmatched parenthesis in issue-label-assign (#13111)

The "keywords" in issue-label-assign are treated as regular expressions,
at least as of the new release of `issue-action` that we're on (see #13105).

https://github.com/Naturalclar/issue-action/blob/de307004a192a08701134a764858d925277cae5a/src/checkKeywords.ts#L11

This unmatched parenthesis is causing our issue assignment workflows to fail.

.github/workflows/issue-label-assign.yml

@@ -90,7 +90,7 @@ jobs:
            {"keywords":["(@aws-cdk/aws-elasticloadbalancingv2-targets)","(aws-elasticloadbalancingv2-targets)","(elasticloadbalancingv2-targets)","(elasticloadbalancingv2 targets)","(elbv2 targets)"],"labels":["@aws-cdk/aws-elasticloadbalancingv2-targets"],"assignees":["njlynch"]},
            {"keywords":["(@aws-cdk/aws-elasticsearch)","(aws-elasticsearch)","(elasticsearch)","(elastic search)","(elastic-search)"],"labels":["@aws-cdk/aws-elasticsearch"],"assignees":["iliapolo"]},
            {"keywords":["(@aws-cdk/aws-emr)","(aws-emr)","(emr)"],"labels":["@aws-cdk/aws-emr"],"assignees":["iliapolo"]},
-           {"keywords":["(@aws-cdk/aws-events)","(aws-events)","(events)","(eventbridge)","event-bridge)"],"labels":["@aws-cdk/aws-events"],"assignees":["rix0rrr"]},
+           {"keywords":["(@aws-cdk/aws-events)","(aws-events)","(events)","(eventbridge)","(event-bridge)"],"labels":["@aws-cdk/aws-events"],"assignees":["rix0rrr"]},
            {"keywords":["(@aws-cdk/aws-events-targets)","(aws-events-targets)","(events-targets)","(events targets)"],"labels":["@aws-cdk/aws-events-targets"],"assignees":["rix0rrr"]},
            {"keywords":["(@aws-cdk/aws-eventschemas)","(aws-eventschemas)","(eventschemas)","(event schemas)"],"labels":["@aws-cdk/aws-eventschemas"],"assignees":["skinny85"]},
            {"keywords":["(@aws-cdk/aws-fms)","(aws-fms)","(fms)"],"labels":["@aws-cdk/aws-fms"],"assignees":["rix0rrr"]},