Support MqttClientOptionsBuilder.WithConnectionUri()

Removed checks for user properties in MQTT v3 and instead ignore them.

Adjusted copyright information in the nuget package specifications.

Reduce the performance cost of Memory<T>.getSpan()

Aspnetcore3bugfixes

DIspose semaphore in MqttChannelAdapter

Added MqttClientUnsubscribeOptionsBuilder

Added receiveTracker to detect whether messages are received from broker.

Add .NET 3.1 target

Add .NET Core 3.1 target that uses ASP.NET Core framework reference instead of NuGet package references

Allow access to full packet on failed connect

Change the name of the variable from requestCode to request

Lost a change while moving from my developement branch to here.

bugfixes