phpunit version update

Author: mmasiukevich

.travis.yml

@@ -18,6 +18,7 @@ install:
 
 script:
   - ./vendor/bin/phpunit --configuration ./phpunit.xml --coverage-clover=coverage.clover
+  - if [ "$TRAVIS_PHP_VERSION" == "7.2" ]; then ./vendor/bin/psalm --config=psalm.xml; fi
 
 after_script:
   - if [ "$TRAVIS_PHP_VERSION" == "7.2" ]; then wget -c -nc --retry-connrefused --tries=0 https://scrutinizer-ci.com/ocular.phar; fi

composer.json

@@ -34,9 +34,9 @@
     "php-service-bus/common": "^v3.0"
   },
   "require-dev": {
-    "phpunit/phpunit": "^7",
+    "phpunit/phpunit": "^8",
     "ext-iconv": "*",
-    "vimeo/psalm": "^3"
+    "vimeo/psalm": "^v3"
   },
   "prefer-stable": true,
   "minimum-stability": "dev",