Fix sandbox by pinning earlier prism image version. (#1365)

Author: mfjarvis

sandbox/Dockerfile

@@ -17,7 +17,7 @@ COPY ./specification ./specification
 RUN jq ".paths += $(cat HealthStatusEndpoint.json)" immunisation-fhir-api.json > updated-spec.json
 
 # Second Stage
-FROM stoplight/prism:5
+FROM stoplight/prism:5.14.2
 
 # Create a non-root user in the Prism container
 USER root
@@ -36,4 +36,4 @@ RUN chown -R appuser:appgroup /usr/src/prism
 USER appuser
 
 # Running the Prism mock command with the OAS file
-CMD ["mock", "-h", "0.0.0.0", "-p", "9000", "immunisation-fhir-api/specification/immunisation-fhir-api.json"]
+CMD ["mock", "-h", "0.0.0.0", "-p", "9000", "immunisation-fhir-api/specification/immunisation-fhir-api.json"]