style: remove or ignore unused imports

The following files had unused imports removed:
- `scripts/30k-image.py`
- `scripts/dl_icons.py`
- `scripts/redact-cast.py`

benchmark/refactor_tools.py

@@ -132,7 +132,7 @@ def find_non_self_methods(path):
         with open(filename, "r") as file:
             try:
                 node = ast.parse(file.read(), filename=filename)
-            except:
+            except:  # noqa: E722
                 pass
             checker = SelfUsageChecker()
             checker.visit(node)