Allow PHP 8; bump dependencies

Author: colinodell

.github/workflows/test.yml

@@ -56,7 +56,7 @@ jobs:
         runs-on: ubuntu-18.04
         strategy:
             matrix:
-                php-version: ['7.1', '7.2', '7.3', '7.4']
+                php-version: ['7.1', '7.2', '7.3', '7.4', '8.0']
 
         steps:
             - uses: actions/checkout@v2
@@ -78,7 +78,7 @@ jobs:
         runs-on: ubuntu-18.04
         strategy:
             matrix:
-                php-version: ['7.1', '7.2', '7.3', '7.4']
+                php-version: ['7.1', '7.2', '7.3', '7.4', '8.0']
 
         steps:
             - uses: actions/checkout@v2
@@ -99,7 +99,7 @@ jobs:
         runs-on: ubuntu-18.04
         strategy:
             matrix:
-                php-version: ['7.1', '7.2', '7.3', '7.4']
+                php-version: ['7.1', '7.2', '7.3', '7.4', '8.0']
 
         steps:
             - uses: actions/checkout@v2

composer.json

@@ -31,10 +31,10 @@
         }
     },
     "require": {
-        "php": "^7.1",
+        "php": "^7.1 || ^8.0",
         "dealerdirect/phpcodesniffer-composer-installer": "^0.7.0",
-        "slevomat/coding-standard": "~6.4.0",
-        "squizlabs/php_codesniffer": "^3.4.0"
+        "slevomat/coding-standard": "~6.4.1",
+        "squizlabs/php_codesniffer": "^3.5.8"
     },
     "require-dev": {
         "symfony/phpunit-bridge": "^5.1"