Use old source code getter

Author: NotWoods

lib/rules/forward-ref-uses-ref.js

@@ -34,7 +34,7 @@ module.exports = {
   },
 
   create(context) {
-    const sourceCode = context.sourceCode;
+    const sourceCode = context.getSourceCode();
     /**
      * @param {ASTNode} node
      * @returns {boolean} If the node represents the identifier `forwardRef`.