Fix command for use on debian

On debian based images this was failing.  I traced it to env -i requiring the full path to the command.

In this PR, I have added $(which cgi-fcgi) to return the full path.

Author: roynasser

php-fpm-healthcheck

@@ -61,7 +61,7 @@ get_fpm_status() {
     if test "$VERBOSE" = 1; then printf "Trying to connect to php-fpm via: %s\\n" "$1"; fi;
 
     # Since I cannot use pipefail I'll just split these in two commands
-    FPM_STATUS=$(env -i REQUEST_METHOD="$REQUEST_METHOD" SCRIPT_NAME="$SCRIPT_NAME" SCRIPT_FILENAME="$SCRIPT_FILENAME" cgi-fcgi -bind -connect "$1" 2> /dev/null)
+    FPM_STATUS=$(env -i REQUEST_METHOD="$REQUEST_METHOD" SCRIPT_NAME="$SCRIPT_NAME" SCRIPT_FILENAME="$SCRIPT_FILENAME" $(which cgi-fcgi) -bind -connect "$1" 2> /dev/null)
     FPM_STATUS=$(echo "$FPM_STATUS" | tail +5)
 
     if test "$VERBOSE" = 1; then printf "php-fpm status output:\\n%s\\n" "$FPM_STATUS"; fi;