benchmark report: on an 8GB Pi 5

Benchmark results of `RUSTFLAGS="-C target-cpu=native" cargo bench --workspace ` run on a Pi 5. I compare with #4 and #40, these look to be respectable results but I don't know how to interpret the "high mild" / "high severe" results. (Next task, hook up a radio and listen for planes) ``` 01 time: [4.8451 ms 4.8691 ms 4.9032 ms] Found 14 outliers among 100 measurements (14.00%) 2 (2.00%) high mild 12 (12.00%) high severe 02 time: [4.7251 ms 4.7318 ms 4.7404 ms] Found 14 outliers among 100 measurements (14.00%) 4 (4.00%) high mild 10 (10.00%) high severe 03 time: [4.5843 ms 4.5912 ms 4.5996 ms] Found 13 outliers among 100 measurements (13.00%) 6 (6.00%) high mild 7 (7.00%) high severe ```