chore: Check Jira ticket number in PR description (#304)

## Summary
Added a check to verify PR description contains a Jira ticket number.

## Ticket:
[OASIS-8321](https://optimizely.atlassian.net/browse/OASIS-8321)

.github/workflows/ticket_reference_check.yml

@@ -0,0 +1,16 @@
+name: Jira ticket reference check
+
+on:
+  pull_request:
+     types: [opened, edited, reopened, synchronize]
+
+jobs:
+
+  jira_ticket_reference_check:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Check for Jira ticket reference
+        uses: optimizely/github-action-ticket-reference-checker-public@master
+        with:
+          bodyRegex: 'OASIS-(?<ticketNumber>\d+)'