Merge pull request #40 from Vinelab/zipkin3

Update version constraints for v2.1.0 release

composer.json

@@ -27,15 +27,15 @@
     "illuminate/queue": "~5.5.0|~5.6.0|~5.7.0|~5.8.0|^6.0|^7.0|^8.0",
     "illuminate/routing": "~5.5.0|~5.6.0|~5.7.0|~5.8.0|^6.0|^7.0|^8.0",
     "illuminate/support": "~5.5.0|~5.6.0|~5.7.0|~5.8.0|^6.0|^7.0|^8.0",
-    "openzipkin/zipkin": "~2.0.2|3.0.x-dev",
+    "openzipkin/zipkin": "~2.0.2|~3.0",
     "psr/http-message": "~1.0",
     "ramsey/uuid": "~3.0|~4.0"
   },
   "require-dev": {
     "google/cloud-pubsub": "^1.18",
-    "guzzlehttp/psr7": "~1.0",
+    "guzzlehttp/psr7": "~1.0|~2.0",
     "mockery/mockery": "~1.0",
-    "php-amqplib/php-amqplib": "~2.8",
+    "php-amqplib/php-amqplib": "~2.8|~3.0",
     "phpunit/phpunit": "~7.0|~8.0",
     "vinelab/http": "~1.5",
     "lucid-arch/laravel-foundation": "^7.0|^8.0",