Fix places where quote replacement lead to issues.

code/iottb/utils/tcpdump_utils.py

@@ -5,18 +5,18 @@ from typing import Optional
 
 
 def check_installed() -> bool:
-    '''Check if tcpdump is installed and available on the system path.'''
+    """Check if tcpdump is installed and available on the system path."""
     return shutil.which('tcpdump') is not None
 
 
 def ensure_installed():
-    '''Ensure that tcpdump is installed, raise an error if not.'''
+    """Ensure that tcpdump is installed, raise an error if not."""
     if not check_installed():
         raise RuntimeError('tcpdump is not installed. Please install it to continue.')
 
 
 def list_interfaces() -> str:
-    '''List available network interfaces using tcpdump.'''
+    """List available network interfaces using tcpdump."""
     ensure_installed()
     try:
         result = subprocess.run(['tcpdump', '--list-interfaces'], capture_output=True, text=True, check=True)