fix 'could not create data dir' on windows (!29)

* fix 'could not create data dir' on windows

from rust doc:

If a parent of the given path doesn't exist, this function will return an error. To create a directory and all its missing parents at the same time, use the create_dir_all function.

src/data.rs

@@ -63,7 +63,7 @@ impl Default for Data {
 	fn default() -> Self {
 		let project_dir = directories::ProjectDirs::from("org", "duniter", "gcli").unwrap();
 		if !project_dir.data_dir().exists() {
-			std::fs::create_dir(project_dir.data_dir()).expect("could not create data dir");
+			std::fs::create_dir_all(project_dir.data_dir()).expect("could not create data dir");
 		};
 		Self {
 			project_dir,