Ignore shellcheck errors in admin ssh keys, fix test ssh connection

ssh without -n or </dev/null will eat all input from the while read loop
This stopped the tests in the test ssh connection to be run

see man ssh for the -n option

bin/admin-test-ssh-keys.sh

@@ -34,6 +34,7 @@ if [ ! -f "${CONFIG_BASE}settings.ini" ]; then
 	exit;
 fi
 # shellcheck source=../config/settings.ini
+# shellcheck disable=SC1094
 source <(grep "=" "${CONFIG_BASE}settings.ini" | sed 's/ *= */=/g')
 if [ -z "${key_age}" ]; then
 	echo "A minimnum key age in days must be set in the settings";
@@ -49,7 +50,7 @@ if [ ! -f "${CONFIG_BASE}${server_list}" ]; then
 	exit;
 fi
 
-SSH="ssh -a -x";
+SSH="ssh -a -x -n";
 # date command
 datecmd="date";
 if date --version 2>&1 | grep -qi "date: illegal option"; then
@@ -92,7 +93,7 @@ while read -r line; do
 		rotate_date="";
 		if [ -f "${LAST_ROTATE}${hostname}_${username}.last-rotate" ]; then
 			# load last rotate timestamp and get YYYY-MM-DD
-			rotate_date=$(${datecmd} -d @"$(cat "${LAST_ROTATE}${hostname}_${username}.last-rotate")" +%F);
+			rotate_date=$(${datecmd} -d "@$(cat "${LAST_ROTATE}${hostname}_${username}.last-rotate")" +%F);
 		fi
 		# check for diff in username / hostname
 		warning_string=""