Fix formatting panic for 0.13.x #1154

Job	Run time
clippy	1m 27s
rustfmt	5s
runefmt	1m 43s
docs	1m 18s
basics	1s
miri_rune	5m 45s
miri_rune_alloc	4m 56s
build_feature (capture-io)	39s
msrv	1m 16s
no_default_features	39s
build_feature (cli,doc)	1m 16s
build_feature (cli,fmt)	1m 18s
no_std_minimal	2m 15s
build_feature (cli)	1m 11s
wasm	51s
build_feature (workspace)	43s
build_feature (languageserver)	57s
build_feature (byte-code)	1m 0s
test	9m 10s
	36m 30s

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