Test on php 8

.github/workflows/ci.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php: [7.4]
+        php: [7.4, 8.0]
     steps:
     - uses: actions/checkout@v1
     - name: Install dependencies

composer.json

@@ -22,8 +22,8 @@
 	},
 	"require-dev":
 	{
-		"phpunit/phpunit": "9.2",
-		"vimeo/psalm": "^3.12"
+		"phpunit/phpunit": "^9.5",
+		"vimeo/psalm": "^4.7"
 	},
 	"autoload":
 	{