fix: escape slash in folder name

Resolves #50

pdf_on_submit/attach_pdf.py

@@ -114,11 +114,12 @@ def publish_progress(percent):
 
 def create_folder(folder, parent):
     """Make sure the folder exists and return it's name."""
-    new_folder_name = "/".join([parent, folder])
-
+    _folder = folder.replace("/", "-")
+    new_folder_name = "/".join([parent, _folder])
+
     if not frappe.db.exists("File", new_folder_name):
-        create_new_folder(folder, parent)
-    
+        create_new_folder(_folder, parent)
+
     return new_folder_name