Remove flatdict dependency.

Author: hscells

pyproject.toml.copy

@@ -9,7 +9,6 @@ dependencies = [
     "click>=8.3.1",
     "collection>=0.1.6",
     "dataclasses-json>=0.6.7",
-    "flatdict>=4.0.1",
     "fnvhash>=0.2.1",
     "furo>=2024.8.6",
     "ir-datasets>=0.5.11",