fix microsoft#3154 missing brace in placehold

according to microsoft/vscode#90250, we need to escape closing brace.

Author: tom-shan

package.json

@@ -368,7 +368,7 @@
               "type": "go",
               "request": "launch",
               "mode": "debug",
-              "program": "^\"${1:\\${file}}\""
+              "program": "^\"${1:\\${file\\}}\""
             }
           },
           {