refactor(core): remove thunderbird

This is not used anymore and replaced my notmuch emacs and mutt. I have mainly
been using the notmuch interaction in emacs so mutt maybe removed soon.

site-modules/core/manifests/packages.pp

@@ -13,7 +13,6 @@ class core::packages {
       'notmuch',
       'offlineimap',
       'silversearcher-ag',
-      'thunderbird',
       'tmux',
       'urlscan',
       'vim',
@@ -28,6 +27,10 @@ class core::packages {
       ensure => installed,
   }
 
+  package { 'thunderbird':
+    ensure => absent
+  }
+
   # core::packages::npm { [
   #     'grunt',
   #     'intelephense',