Bump PHPUnit to version 8

- the earliest version that is currently supported and works with
  PHP7.4
- PHPUnit 8 no longer works with the upstream dbunit, which has
  been abandoned
- removed outdated config from tests/phpunit.xml in favour of
  default behaviour
- Replace phpunit/dbunit with a supported fork, misantron/dbunit
- Updated clases used, method signitures and documentation as
  needed due to that

.github/actions/mysql_bootstrap_pdo.php

@@ -12,9 +12,9 @@
 /**
  * Returns the database connection to your test databse.
  * Modify as required to return a connection to your test db.
- * @return PHPUnit_Extensions_Database_DB_IDatabaseConnection
+ * @return PHPUnit\DbUnit\Database\Connection
  */
 function getConnectionToTestDB() {
     $pdo = new PDO('mysql:host=172.18.0.1;dbname=doctrine;charset=UTF8', 'user', 'password');
-    return new PHPUnit_Extensions_Database_DB_DefaultDatabaseConnection($pdo);
+    return new PHPUnit\DbUnit\Database\DefaultConnection($pdo);
 }

.github/actions/sqlite_bootstrap_pdo.php

@@ -12,12 +12,12 @@
 /**
  * Returns the database connection to your test databse.
  * Modify as required to return a connection to your test db.
- * @return PHPUnit_Extensions_Database_DB_IDatabaseConnection
+ * @return PHPUnit\DbUnit\Database\DefaultConnection
  */
 function getConnectionToTestDB() {
     $sqliteFile = '/tmp/gocdb.sqlite';
     $pdo = new PDO("sqlite:" . $sqliteFile);
-    return new PHPUnit_Extensions_Database_DB_DefaultDatabaseConnection($pdo, 'sqlite');
+    return new PHPUnit\DbUnit\Database\DefaultConnection($pdo, 'sqlite');
 }
 
 ?>

composer.json

@@ -7,8 +7,8 @@
     "doctrine/annotations": "*"
     },
     "require-dev": {
-        "phpunit/phpunit": "4.8.*",
-        "phpunit/dbunit": ">=1.2",
+        "phpunit/phpunit": "8.*",
+        "misantron/dbunit": "*",
         "phpmd/phpmd": "^2.13",
         "squizlabs/php_codesniffer": "^3.7",
         "taq/pdooci": "^1.0"