Bug in BOSSA (bossac) on macOS prevents flashing parts

### Describe the problem

There is a bug reported in a couple of different places in the `bossac` command line tool for flashing Microchip SAM MCUs. The fix is straightforward and available in this [PR](https://github.com/arduino/BOSSA/pull/2), but it has been sitting there since August 2021.

As there is no issue tracker for the Arduino BOSSA repo, I'm opening this issue to hopefully draw attention to the PR.

Although `bossac` `1.9.1-arduino2` (the latest) has a patch applied relative to the upstream BOSSA for this flush operation, as implemented, it doesn't work on macOS (it may work on Linux, I don't know).

### To reproduce

Attempt to flash a SAM5Ex part. It will fail verification

### Expected behavior

I expect it to succeed.

### Arduino IDE version

There is a bug reported in a couple of different places in the `bossac` command line tool for flashing Microchip SAM MCUs. The fix is straightforward and available in this [PR](https://github.com/arduino/BOSSA/pull/2), but it has been sitting there since August 2021. As there is no issue tracker for the Arduino BOSSA repo, I'm opening this issue to hopefully draw attention to the PR.

### Operating system

macOS

### Operating system version

15.2

### Additional context

_No response_

### Issue checklist

- [x] I searched for previous reports in [the issue tracker](https://github.com/arduino/arduino-ide/issues?q=)
- [x] I verified the problem still occurs when using the latest [nightly build](https://www.arduino.cc/en/software#nightly-builds)
- [x] My report contains all necessary details

Start with the bossac command-line tool and review the linked BOSSA PR, then reproduce flashing a SAM5Ex part on macOS 15.2. Done means the flash completes verification successfully on macOS; compare the result with the reported failure.

Written by the indexing model from the issue text.