Update test environment to fix tests on legacy PHP 7.2 with PHPUnit 8.5

Author: clue

.github/workflows/ci.yml

@@ -32,10 +32,7 @@ jobs:
           coverage: xdebug
           ini-file: development
       - run: composer install
-      - run: vendor/bin/phpunit --coverage-text --coverage-clover=clover.xml
-        if: ${{ matrix.php >= 7.3 }}
-      - run: vendor/bin/phpunit --coverage-text --coverage-clover=clover.xml -c phpunit.xml.legacy
-        if: ${{ matrix.php < 7.3 }}
+      - run: vendor/bin/phpunit --coverage-text --coverage-clover=clover.xml ${{ matrix.php < 7.3 && '-c phpunit.xml.legacy' || '' }}
       - name: Check 100% code coverage
         shell: php {0}
         run: |

composer.json

@@ -18,7 +18,7 @@
         "react/promise": "^3.2 || ^2.10 || ^1.2.1"
     },
     "require-dev": {
-        "phpunit/phpunit": "^9.6 || ^5.7 || ^4.8.36"
+        "phpunit/phpunit": "^9.6 || ^8.5 || ^5.7 || ^4.8.36"
     },
     "autoload": {
         "psr-4": {