[pmon]: add psmisc to bring fuser that dentifies processes that are u…

…sing files or sockets (#7509)

fuser support is required since new cisco hardware watchdog plugin uses them to check anyone else use's /dev/watchdogX resource. The actual validation happens in the platform code, but the package is required for pmon container. Currently the /dev/watchdogX is being used by cisco platform-monitor service. Cisco chassis level watchdog plugin uses "fuser" to claim the watchdog release from platform-monitor service.

dockers/docker-platform-monitor/Dockerfile.j2

@@ -23,7 +23,8 @@ RUN apt-get update &&   \
         python-smbus    \
         python3-smbus   \
         dmidecode       \
-        i2c-tools
+        i2c-tools       \
+        psmisc
 
 # TODO: Remove these lines once we no longer need Python 2
 RUN apt-get install -f -y python-dev python-pip