fix(TextToImage): Update testing provider to new interface

Signed-off-by: Marcel Klehr <mklehr@gmx.net>

apps/testing/lib/Provider/FakeText2ImageProvider.php

@@ -41,4 +41,8 @@ class FakeText2ImageProvider implements IProvider {
 	public function getExpectedRuntime(): int {
 		return 1;
 	}
+
+	public function getId(): string {
+		return 'testing-fake-text2image-provider';
+	}
 }