Add Ruby 4, truffle ruby and jruby to build (#167)

* Add Ruby 4, truffle ruby and jruby to build
* Updated tests to work on jruby

There was only one issue with the test suite, that on jruby TCPServer.new cannot be given a nil port, it must be an integer. However passing 0 should have the same effect on both cruby and jruby.

Author: iainbeeston

.github/workflows/build.yml

@@ -6,7 +6,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest]
-        ruby: ['2.3', '2.4', '2.5', '2.6', '2.7', '3.0', '3.1', '3.2', '3.3', '3.4', '3.5']
+        ruby: ['2.3', '2.4', '2.5', '2.6', '2.7', '3.0', '3.1', '3.2', '3.3', '3.4', '4.0', 'jruby-10.1.0', 'truffleruby-33']
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v3

spec/fake_server.rb

@@ -34,7 +34,7 @@ class MQTT::FakeServer
   #
   # If no port is given, bind to a random port number
   # If no bind address is given, bind to localhost
-  def initialize(port=nil, bind_address='127.0.0.1')
+  def initialize(port=0, bind_address='127.0.0.1')
     @port = port
     @address = bind_address
     @pings_received = 0