Removing mutation

[sagenschneider]

No description provided.

[github-actions]

Change impact: 140,035 ✅ OK

field	value
files changed	5
scope	vs origin/main (merge-base..HEAD)

Files to consider for refactoring

cost	file	existing	new	fns changed	fns new
21,316	impact_gate/report.py	20,414	902	3	2
5,091	impact_gate/cli.py	2,907	2,184	4	1
896	impact_gate/config.py	0	896	0	2
584	tests/test_cli.py	0	584	0	7
120	tests/test_data.py	0	120	0	2