chore: Update AsyncAPI spec version to 2.6.0

[timonback]

• Read the new spec
  • Message#messageId
  • SchemaFormat + Example via annotation
• Alphabetic sorting of topics
• Update imports
• asyncapi.json endpoint

[timonback]

Imports need to be updated as well -> Done

[sam0r040]

@Pakisan With updating from 2.0.0 to 2.6.0 we noticed that the properties for Message and ChannelBinding have changed the value of the Bindings map from an extension of the Binding type to Object. For Example:

private Map<String, ? extends MessageBinding> bindings;

to

private Map<String, Object> bindings;

this requires some casting for us, was this intended? Did you consider using Map<String,?> instead?

[Pakisan]

@sam0r040 hi!

I'll think what is the best variant to fix it. Open to your proposals, in related issue

asyncapi/jasyncapi#126