Run tests on PHP 8

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