Use single quotes for plugin manager. (#175)

Author: chesn0k

templates/_plugin-manager/attribute/src/Plugin/Example/Foo.php.twig

@@ -14,9 +14,9 @@ use Drupal\{{ machine_name }}\{{ class_prefix }}PluginBase;
  * Plugin implementation of the {{ plugin_type }}.
  */
 #[{{ class_prefix }}(
-  id: "foo",
-  label: new TranslatableMarkup("Foo"),
-  description: new TranslatableMarkup("Foo description."),
+  id: 'foo',
+  label: new TranslatableMarkup('Foo'),
+  description: new TranslatableMarkup('Foo description.'),
 )]
 final class Foo extends {{ class_prefix }}PluginBase {
 

tests/functional/Generator/_plugin_manager/_attribute/src/Plugin/Bar/Foo.php

@@ -12,9 +12,9 @@
  * Plugin implementation of the bar.
  */
 #[Bar(
-  id: "foo",
-  label: new TranslatableMarkup("Foo"),
-  description: new TranslatableMarkup("Foo description."),
+  id: 'foo',
+  label: new TranslatableMarkup('Foo'),
+  description: new TranslatableMarkup('Foo description.'),
 )]
 final class Foo extends BarPluginBase {