split fira sans copyright notice into multiple lines

Author: pietroalbini

.reuse/dep5

@@ -48,7 +48,8 @@ Copyright: 1991-2022 Unicode, Inc. All rights reserved.
 License: Unicode-DFS-2016
 
 Files: src/librustdoc/html/static/fonts/FiraSans*
-Copyright: 2014, Mozilla Foundation, 2014, Telefonica S.A.
+Copyright: 2014, Mozilla Foundation
+           2014, Telefonica S.A.
 License: OFL-1.1
 
 Files: src/librustdoc/html/static/fonts/NanumBarun*