[show] fix get routing stack routine (#2137)

- What I did
Fixed error message: "Failed to get routing stack: a bytes-like object is required, not 'str'" introduced by #2117

- How I did it
Add missing 'text' parameter

- How to verify it
Run on switch

Signed-off-by: Stepan Blyschak <[email protected]>

show/main.py

@@ -77,7 +77,7 @@ def get_routing_stack():
     command = "sudo docker ps | grep bgp | awk '{print$2}' | cut -d'-' -f3 | cut -d':' -f1 | head -n 1"
 
     try:
-        stdout = subprocess.check_output(command, shell=True, timeout=COMMAND_TIMEOUT)
+        stdout = subprocess.check_output(command, shell=True, text=True, timeout=COMMAND_TIMEOUT)
         result = stdout.rstrip('\n')
     except Exception as err:
         click.echo('Failed to get routing stack: {}'.format(err), err=True)