return self on several setter/builder methods for more consistent behaviour (#1609)

src/Monolog/Logger.php

@@ -272,9 +272,11 @@ class Logger implements LoggerInterface, ResettableInterface
      *
      * @param bool $micro True to use microtime() to create timestamps
      */
-    public function useMicrosecondTimestamps(bool $micro): void
+    public function useMicrosecondTimestamps(bool $micro): self
     {
         $this->microsecondTimestamps = $micro;
+
+        return $this;
     }
 
     /**