chore(frontends/lean): fix style

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

src/frontends/lean/info_manager.cpp

@@ -4,6 +4,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 
 Author: Leonardo de Moura
 */
+#include <vector>
 #include "library/choice.h"
 #include "frontends/lean/info_manager.h"
 #include "frontends/lean/pp_options.h"

src/frontends/lean/info_manager.h

@@ -6,6 +6,7 @@ Author: Leonardo de Moura
 */
 #pragma once
 #include <memory>
+#include <vector>
 #include "util/thread.h"
 #include "kernel/expr.h"
 #include "library/io_state_stream.h"

src/frontends/lean/server.cpp

@@ -5,6 +5,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Leonardo de Moura
 */
 #include <string>
+#include <functional>
 #include "frontends/lean/server.h"
 #include "frontends/lean/parser.h"