lib: remove semicolon in preparation for babel/eslint-parser update

eslint-babel-plugin will complain about this semicolon when we update
to 7.14.15.

PR-URL: #39094
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: Trott

lib/internal/source_map/source_map.js

@@ -275,7 +275,7 @@ class SourceMap {
          sourceColumnNumber, name]
       );
     }
-  };
+  }
 }
 
 /**