refactor: Update apt-cacher setup script to use IP address instead of hostname for the proxy server

gui/postman.sh

@@ -0,0 +1 @@
+snap install postman

gui/setup.sh

@@ -6,4 +6,7 @@ chmod +x ./gui/spotify.sh
 ./gui/spotify.sh
 
 chmod +x ./gui/bluemail.sh
-./gui/bluemail.sh
+./gui/bluemail.sh
+
+chmod +x ./gui/postman.sh
+./gui/postman.sh