fix: reformat upload files

src/services/courses/thumbnails.py

@@ -0,0 +1,15 @@
+import os
+
+
+async def upload_thumbnail(thumbnail_file, name_in_disk):
+    contents = thumbnail_file.file.read()
+    try:
+        with open(f"content/uploads/img/{name_in_disk}", 'wb') as f:
+            f.write(contents)
+            f.close()
+
+    except Exception as e:
+        print(e)
+        return {"message": "There was an error uploading the file"}
+    finally:
+        thumbnail_file.file.close()