Increase default RAM allocation for Gatus (#16601)

Gatus install was failing with the existing memory defaults (512M) due to thrashing from memory pressure while compiling the package. Bumped to 2048M as the same issue occurred when using 1024M. 

Gatus LXC is hovering around 150M post install so this could be bumped down after the install completed but there is no installation time only setting as far as I am aware.

ct/gatus.sh

@@ -19,11 +19,11 @@ if [[ -z "${var_os:-}" ]] && command -v pveversion >/dev/null 2>&1; then
 fi
 
 if [[ "${var_os:-}" == "alpine" ]]; then
-  var_ram="${var_ram:-512}"
+  var_ram="${var_ram:-2048}"
   var_disk="${var_disk:-3}"
   var_version="${var_version:-3.24}"
 else
-  var_ram="${var_ram:-512}"
+  var_ram="${var_ram:-2048}"
   var_disk="${var_disk:-4}"
   var_version="${var_version:-13}"
 fi