MRG: fix `remaining_bp` output from sourmash gather #5208

Job	Run time
Check	31s
test (beta)	1m 34s
test_all_features	10m 53s
test (stable)	1m 41s
test (windows)	4m 44s
test (macos)	2m 39s
coverage	9m 38s
Lints (beta)	36s
Lints (stable)	31s
Publish (dry-run)	6m 6s
Check if wasm-pack builds a valid package for the sourmash crate	2m 6s
Run tests under wasm32-wasi	1m 24s
Check if cbindgen runs cleanly for generating the C headers	6m 16s
minimum_rust_version	7m 44s
	56m 23s

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