fix: prepend paths with "/" to account for root

* Files showed up in OpossumUI correctly but attributions where not showing up at all
* Prepending a "/" to the paths in resourcesToAttributions fixes this
* This is because OpossumUI always considers "/" to be the root for all file paths apparently

Author: abraemer

src/opossum_lib/scancode/resource_tree.py

@@ -95,7 +95,8 @@ def create_attribution_mapping(
     resourcesToAttributions = {}  # path -> [attributionUUID]
 
     def process_node(node: Node) -> None:
-        path = node.file.path
+        # the / is required by OpossumUI
+        path = "/" + node.file.path
         attributions = get_attribution_info(node.file)
         attributionIDs = []
         for attribution in attributions: