Issue #2340123 followup by Mile23: Setting cache tags can be tricky: use...

Issue #2340123 followup by Mile23: Setting cache tags can be tricky: use strings instead of nested arrays to improve DX.

core/tests/Drupal/Tests/Core/Cache/CacheTest.php

@@ -133,7 +133,7 @@ public function testDeleteTags() {
    * @expectedExceptionMessage Cache tags must be strings, array given.
    */
   public function testInvalidateTags() {
-    Cache::deleteTags(['node' => [2, 3, 5, 8, 13]]);
+    Cache::invalidateTags(['node' => [2, 3, 5, 8, 13]]);
   }
 
 }