NPA-6547: bump OAS version to 1.19.0 (#326)

# Pull Request

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https://nhsd-jira.digital.nhs.uk/browse/NPA-6547

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- Increment version for release
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Author: hatwell

specification/validated-relationships-service-api.yaml

@@ -3,7 +3,7 @@
 openapi: "3.0.0"
 info:
   title: "Validated Relationships Service API"
-  version: "1.18.0"
+  version: "1.19.0"
   description: |
     ## Overview
     This service underpins the National Proxy Programme whose core objective is to allow Patients to be supported with