Improve support Symfony 7

Author: Oleg Maksimenko

src/Wrep/Daemonizable/Command/EndlessCommand.php

@@ -244,7 +244,7 @@ public function setCode(callable $code): static
      * @throws LogicException When this abstract method is not implemented
      * @see    setCode()
      */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         return parent::execute($input, $output);
     }

tests/Wrep/Daemonizable/Command/EndlessCommandTest.php

@@ -110,8 +110,10 @@ public function testInterruptSigtermFromDifferentContext(): void
  */
 class EndlessSelfTerminatingCommand extends EndlessCommand
 {
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         posix_kill(posix_getpid(), SIGTERM);
+
+        return self::SUCCESS;
     }
 }