Drupal 9 compatibility

Please review the patch.

Looks like the failing tests are due to changing the assertions

-    $this->assertInternalType('int', $actual[0]->body['You are number']);
-    $this->assertInternalType('string', $actual[0]->body['Where am I']);
-    $this->assertInternalType('boolean', $actual[0]->body['World of number two']);
-    $this->assertInternalType('string', $actual[0]->body['Question']);
-    $this->assertInternalType('float', $actual[0]->body['Michael']);
+    $this->assertIsInt($actual[0]->body['You are number']);
+    $this->assertIsString($actual[0]->body['Where am I']);
+    $this->assertIsBool( $actual[0]->body['World of number two']);
+    $this->assertIsString( $actual[0]->body['Question']);
+    $this->assertIsFloat($actual[0]->body['Michael']);

The indenting is also off here:

-    "galbar/jsonpath": "^1.0"
+    "galbar/jsonpath": "^1.0",
+      "drupal/core": "^8 || ^9"

This should hopefully pass tests.

Thanks for the patch!