Edge TPU compiler `sudo` fix (#6531)

* Edge TPU compiler sudo fix

Allows for auto-install of Edge TPU compiler on non-sudo systems like the YOLOv5 Docker image.

@kalenmike

* Update export.py

* Update export.py

* Update export.py

export.py

 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'
+        cmd = 'edgetpu_compiler --version >/dev/null'
         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:
             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 -',
                       'echo "deb https://packages.cloud.google.com/apt coral-edgetpu-stable main" | sudo tee /etc/apt/sources.list.d/coral-edgetpu.list',
                       'sudo apt-get update',
                       'sudo apt-get install edgetpu-compiler']:
-                subprocess.run(c, shell=True, check=True)
+                subprocess.run(c if sudo else c.replace('sudo ', ''), shell=True, check=True)
         ver = subprocess.run(cmd, shell=True, capture_output=True, check=True).stdout.decode().split()[-1]
 
         LOGGER.info(f'\n{prefix} starting export with Edge TPU compiler {ver}...')