Edge TPU export 'list index out of range' fix (#6533)

export.py

@@ -315,10 +315,10 @@ def export_tflite(keras_model, im, file, int8, data, ncalib, prefix=colorstr('Te
 def export_edgetpu(keras_model, im, file, prefix=colorstr('Edge TPU:')):
     # YOLOv5 Edge TPU export https://coral.ai/docs/edgetpu/models-intro/
     try:
-        cmd = 'edgetpu_compiler --version >/dev/null'
+        cmd = 'edgetpu_compiler --version'
         help_url = 'https://coral.ai/docs/edgetpu/compiler/'
         assert platform.system() == 'Linux', f'export only supported on Linux. See {help_url}'
-        if subprocess.run(cmd, shell=True).returncode != 0:
+        if subprocess.run(cmd + ' >/dev/null', shell=True).returncode != 0:
             LOGGER.info(f'\n{prefix} export requires Edge TPU compiler. Attempting install from {help_url}')
             sudo = subprocess.run('sudo --version >/dev/null', shell=True).returncode == 0  # sudo installed on system
             for c in ['curl https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -',