isGlob('?') returns false

This seems wrong to me?

In particular, it's causing `fastGlob("?/*")` to fail.
```sh
mkdir a
touch a/test
node -p 'require("fast-glob").sync("?/test")'
# prints []
node -p 'require("fast-glob").sync("{?,?}/test")'
# prints [ 'a/test' ]
```
