Use pathlib module to work with workflow artifact archive paths

The sketches report workflow artifact is downloaded to a temporary folder and extracted. This requires working with
paths. The pathlib module provides convenient and safe path handling and so should be used whenever there is significant
involvement of paths in code.

Author: per1234

reportsizedeltas/reportsizedeltas.py

@@ -267,17 +267,18 @@ def get_artifact(self, artifact_data):
         """
         # Create temporary folder
         artifact_folder_object = tempfile.TemporaryDirectory(prefix="reportsizedeltas-")
+        artifact_folder_path = pathlib.Path(artifact_folder_object.name)
         try:
-            artifact_zip_file = artifact_folder_object.name + "/" + artifact_data["name"] + ".zip"
+            artifact_zip_file_path = artifact_folder_path.joinpath(artifact_data["name"] + ".zip")
             # Download artifact
-            with open(file=artifact_zip_file, mode="wb") as out_file:
+            with artifact_zip_file_path.open(mode="wb") as out_file:
                 with self.raw_http_request(url=artifact_data["archive_download_url"]) as fp:
                     out_file.write(fp.read())
 
             # Unzip artifact
-            with zipfile.ZipFile(file=artifact_zip_file, mode="r") as zip_ref:
-                zip_ref.extractall(path=artifact_folder_object.name)
-            os.remove(artifact_zip_file)
+            with zipfile.ZipFile(file=artifact_zip_file_path, mode="r") as zip_ref:
+                zip_ref.extractall(path=artifact_folder_path)
+            artifact_zip_file_path.unlink()
 
             return artifact_folder_object