fix: Perform release builds with ContinuousIntegrationBuild=true
fix: Perform release builds with ContinuousIntegrationBuild=true

(The build needs to be done this way, not just the packing.)

Fixes #175

Signed-off-by: Jon Skeet <8a9602d66334021c18cbf0bdb2fa15f4cb6de9df@google.com>

cloudevents/sdk-csharp,cloudevents/sdk-csharp