latest stable pekko releases

[pjfanning]

Seems best to test with latest releases.
Also, now removes the pekko-protobuf dependency which is not needed and causes issues if you want to use Pekko 1.1.x - which removes this jar.

[pjfanning]

test failures seem possibly unrelated

[error] (kamon-apache-httpclient / Test / test) sbt.TestsFailedException: Tests unsuccessful
[error] (kamon-apache-cxf / Test / test) sbt.TestsFailedException: Tests unsuccessful

The issues appear to be with netty getting access to open ports. e.g.

[info] The apache httpclient taking HttpRequest
[info] - should create client span when using execute(...) *** FAILED ***
[info]   org.mockserver.httpclient.SocketConnectionException: Unable to connect to socket localhost/127.0.0.1:38415
[info]   at org.mockserver.httpclient.NettyHttpClient.sendRequest(NettyHttpClient.java:200)
[info]   at org.mockserver.client.MockServerClient.sendRequest(MockServerClient.java:393)
[info]   at org.mockserver.client.MockServerClient.sendRequest(MockServerClient.java:429)
[info]   at org.mockserver.client.MockServerClient.upsert(MockServerClient.java:1494)
[info]   at org.mockserver.client.ForwardChainExpectation.respond(ForwardChainExpectation.java:84)
[info]   at kamon.instrumentation.apache.httpclient.util.MockServerExpectations.simpleGetExpectation(MockServerExpectations.scala:19)
[info]   at kamon.instrumentation.apache.httpclient.HttpRequestSpec$$anonfun$1$$anonfun$apply$mcV$sp$1.apply(HttpRequestSpec.scala:49)
[info]   at kamon.instrumentation.apache.httpclient.HttpRequestSpec$$anonfun$1$$anonfun$apply$mcV$sp$1.apply(HttpRequestSpec.scala:48)
[info]   at org.scalatest.OutcomeOf$class.outcomeOf(OutcomeOf.scala:85)
[info]   at org.scalatest.OutcomeOf$.outcomeOf(OutcomeOf.scala:104)
[info]   ...
[info]   Cause: io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection refused: localhost/127.0.0.1:38415
[info]   ...
[info]   Cause: java.net.ConnectException: Connection refused
[info]   at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
[info]   at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:716)
[info]   at io.netty.channel.socket.nio.NioSocketChannel.doFinishConnect(NioSocketChannel.java:330)
[info]   at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.finishConnect(AbstractNioChannel.java:334)
[info]   at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:710)
[info]   at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:658)
[info]   at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:584)
[info]   at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:496)
[info]   at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:986)
[info]   at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
[info]   ...