asciidoctor-with-extensions: add 'tilt' gem

tilt was added to asciidoctor in 2023, and I think it's good to sync up
asciidoctor-with-extensions, so that it becomes a *superset* of the base
asciidoctor package.

tilt is a dependency for
https://docs.asciidoctor.org/asciidoctor/latest/convert/templates/.

pkgs/by-name/as/asciidoctor-with-extensions/Gemfile

@@ -11,3 +11,4 @@ gem 'asciidoctor-revealjs'
 gem 'coderay'
 gem 'pygments.rb'
 gem 'rouge'
+gem 'tilt'

pkgs/by-name/as/asciidoctor-with-extensions/Gemfile.lock

@@ -129,6 +129,7 @@ GEM
       rb-inotify (~> 0.9, >= 0.9.7)
     stringio (3.1.8)
     thread_safe (0.3.6)
+    tilt (2.6.1)
     time (0.4.1)
       date
     treetop (1.6.18)
@@ -152,6 +153,7 @@ DEPENDENCIES
   coderay
   pygments.rb
   rouge
+  tilt
 
 BUNDLED WITH
    2.7.2

pkgs/by-name/as/asciidoctor-with-extensions/gemset.nix

@@ -676,6 +676,16 @@
     };
     version = "0.3.6";
   };
+  tilt = {
+    groups = [ "default" ];
+    platforms = [ ];
+    source = {
+      remotes = [ "https://rubygems.org" ];
+      sha256 = "0w27v04d7rnxjr3f65w1m7xyvr6ch6szjj2v5wv1wz6z5ax9pa9m";
+      type = "gem";
+    };
+    version = "2.6.1";
+  };
   time = {
     dependencies = [ "date" ];
     groups = [ "default" ];