backout some of phpunit deprecations so phpunit 7 can still be run in Drupal 8

tests/src/Kernel/Plugin/migrate_plus/data_parser/SimpleXmlTest.php

@@ -132,7 +132,7 @@ class SimpleXmlTest extends KernelTestBase {
     $this->configuration['urls'][0] = $url;
     $this->expectException(MigrateException::class);
     // Newer versions of libxml mark it as an error 76, older ones as 73.
-    $this->expectExceptionMessageMatches('/^Fatal Error 7[0-9]/');
+    $this->expectExceptionMessageRegExp('/^Fatal Error 7[0-9]/');
     $parser = $this->pluginManager->createInstance('simple_xml', $this->configuration);
     $parser->next();
   }
@@ -147,7 +147,7 @@ class SimpleXmlTest extends KernelTestBase {
     $this->configuration['urls'][0] = $url;
 
     $this->expectException(MigrateException::class);
-    $this->expectExceptionMessageMatches('/^Fatal Error 76/');
+    $this->expectExceptionMessageRegExp('/^Fatal Error 76/');
 
     $parser = $this->pluginManager->createInstance('simple_xml', $this->configuration);
     $parser->next();
@@ -163,7 +163,7 @@ class SimpleXmlTest extends KernelTestBase {
     $this->configuration['urls'][0] = $url;
 
     $this->expectException(MigrateException::class);
-    $this->expectExceptionMessageMatches('/^Fatal Error 46/');
+    $this->expectExceptionMessageRegExp('/^Fatal Error 46/');
     $parser = $this->pluginManager->createInstance('simple_xml', $this->configuration);
     $parser->next();
   }