snippets: nrf70-debug: Update shell stack size

Shell stack size is now increased, but forgot to update the debug
snippet.

Signed-off-by: Chaitanya Tata <Chaitanya.Tata@nordicsemi.no>

Author: krish2718

snippets/nrf70-debug/overlay-debug.conf

@@ -5,7 +5,7 @@
 #
 
 CONFIG_SHELL=y
-CONFIG_SHELL_STACK_SIZE=4096
+CONFIG_SHELL_STACK_SIZE=4200
 CONFIG_NET_SHELL=y
 CONFIG_SHELL_GETOPT=y
 CONFIG_SHELL_CMDS_RESIZE=n