[DependencyInjection] add missing expectedDeprecation on testLegacyGet

Author: Amrouche Hamza

Tests/ContainerTest.php

@@ -220,6 +220,7 @@ public function testNormalizeIdKeepsCase()
 
     /**
      * @group legacy
+     * @expectedDeprecation Service identifiers will be made case sensitive in Symfony 4.0. Using "Foo" instead of "foo" is deprecated since version 3.3.
      * @expectedDeprecation Generating a dumped container without populating the method map is deprecated since 3.2 and will be unsupported in 4.0. Update your dumper to generate the method map.
      * @expectedDeprecation Generating a dumped container without populating the method map is deprecated since 3.2 and will be unsupported in 4.0. Update your dumper to generate the method map.
      * @expectedDeprecation Generating a dumped container without populating the method map is deprecated since 3.2 and will be unsupported in 4.0. Update your dumper to generate the method map.