vscode(launch): avoid deprecated variable

Apparently the `workspaceRoot` variable is no longer suggested (even if
it seems to work), but `workspaceFolder` is.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

.vscode/launch.json

@@ -5,8 +5,8 @@
       "type": "node",
       "request": "launch",
       "name": "Debug Tests",
-      "program": "${workspaceRoot}/node_modules/.bin/jest",
-      "cwd": "${workspaceRoot}",
+      "program": "${workspaceFolder}/node_modules/.bin/jest",
+      "cwd": "${workspaceFolder}",
       // to restrict running to a particular test case, add something like "--testNamePattern=/deploy"
       "args": ["--runInBand", "--config", "jest.config.js"],
       "windows": {