Release 2.8.0

[jskeet]

Changes since 2.7.1:

• Add explicit .NET 8 target to all packages.
• Removed dependencies that are already included in the framework, for suitable targets.
• Use a framework reference to Microsoft.AspNetCore.App instead of package references,
  for the .NET 8 target
• Release CloudNative.CloudEvents.Mqtt as 3.8.0, bumping the major
  version to reflect adopting MQTTnet version 4.3.6.1152.
  Fixes #269.
• Other dependency updates:
  • AMQPNetLite and AMQPNetLite.Serialization: 2.4.2 => 2.4.11
  • Apache.Avro: 1.11.1 => 1.11.3
  • Newtonsoft.Json: 13.0.2 => 13.0.3
  • Google.Protobuf: 3.22.0 => 3.27.3
  • Confluent.Kafka: 1.6.3 => 1.9.3
    • See #297 for
      consideration of a bump to 2.x.
  • Only for netstandard2.0 and netstandard2.1 targets:
    • System.Text.Encodings.Web: 6.0.0 => 8.0.0
    • System.Text.Json: 5.0.2 => 8.0.4

[jskeet]

@captainsafia if you're happy to review this, that would be great :)

(Deliberately no change in the MQTT project file - it derives everything from the existing variables. We'll need a post-release change.)

[captainsafia]

[captainsafia]

Suggested change

	- System.Text.Json: 5.0.2 => 8.0.4
	- System.Text.Json: 5.0.2 => 8.0.4 (only used in netstandard2.0 and netstandard2.1 targets)

A bit pedantic, but I like the clarification that you provided for System.Text.Encodings.Web below. Maybe we can colocate the two under a separate heading?

[jskeet]

Yes, good plan, will do that tomorrow morning UK time. And more pedantry is always fine by me :) Thanks!

[jskeet]

Have updated, and moved the bit about targeting .NET 8 and using framework references where possible to the top, so that the conditionality makes more sense. Please take a look - docs are so important and I really appreciate your input :)

[captainsafia]

A few more nits

[jskeet]

Thanks for the extra nits - I'll apply those tomorrow morning UK time, then merge (as I think those changes would be entirely uncontroversial). I'll then kick off a release.
Thanks so much!