utils.py: update file not found exception message #1017

Job	Run time
Detect which file has changed	5s
prepare-environment / prepare	3s
python-lint	6s
yaml-lint	-1s
markdown-lint	-1s
action-lint	-1s
validate-generated-documentation	0s
documentation	0s
validate-documentation-style	0s
integration-tests-latest-infrahub	0s
unit-tests	0s
	11s

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