fix: fix is_in_apt function for virtual packages (#41)

Signed-off-by: Stefan Dej <meteyou@gmail.com>

Author: meteyou

src/common.sh

@@ -12,7 +12,11 @@ function is_installed(){
 function is_in_apt(){
   # Checks if a package is in the apt repo, returns 1 if exists and 0 if not
   # Usage is_in_apt <package_name>
-  if [ $(apt-cache policy $1 |  wc  | awk '{print $1}') -gt 0 ]; then
+
+  local output
+  output=$(apt-cache search --names-only "^${1}$")
+
+  if [ -n "$output" ]; then
     echo 1
   else
     echo 0