machine/arduino-nano33: remove (d)ebug flag to reduce console noise when flashing

Signed-off-by: deadprogram <ron@hybridgroup.com>

targets/arduino-nano33.json

@@ -1,6 +1,6 @@
 {
     "inherits": ["atsamd21g18a"],
     "build-tags": ["sam", "atsamd21g18a", "arduino_nano33"],
-    "flash-command": "bossac -d -i -e -w -v -R -U --port={port} --offset=0x2000 {bin}",
+    "flash-command": "bossac -i -e -w -v -R -U --port={port} --offset=0x2000 {bin}",
     "flash-1200-bps-reset": "true"
 }