Demos: update Viewport#set_content() to #content=()

demo/chat

@@ -24,7 +24,7 @@ class ChatDemo
     @textarea.show_line_numbers = false
 
     @viewport = Bubbles::Viewport.new(width: 30, height: 5)
-    @viewport.set_content("Welcome to the chat room!\nType a message and press Enter to send.")
+    @viewport.content = "Welcome to the chat room!\nType a message and press Enter to send."
 
     @messages = []
     @sender_style = Lipgloss::Style.new.foreground("5")
@@ -46,7 +46,7 @@ class ChatDemo
 
       if @messages.any?
         content = Lipgloss::Style.new.width(@viewport.width).render(@messages.join("\n"))
-        @viewport.set_content(content)
+        @viewport.content = content
       end
       @viewport.goto_bottom
 
@@ -58,7 +58,7 @@ class ChatDemo
       when "enter"
         @messages << "#{@sender_style.render("You: ")}#{@textarea.value}"
         content = Lipgloss::Style.new.width(@viewport.width).render(@messages.join("\n"))
-        @viewport.set_content(content)
+        @viewport.content = content
         @textarea.reset
         @viewport.goto_bottom
       end

demo/glamour

@@ -64,7 +64,7 @@ class GlamourDemo
     glamour_render_width = width - horizontal_frame_size - glamour_gutter
 
     rendered = Glamour.render(CONTENT, style: "auto", width: glamour_render_width)
-    @viewport.set_content(rendered)
+    @viewport.content = rendered
 
     @help_style = Lipgloss::Style.new.foreground("241")
   end

demo/pager

@@ -119,7 +119,7 @@ class PagerDemo
           width: message.width,
           height: message.height - vertical_margin_height
         )
-        @viewport.set_content(@content)
+        @viewport.content = @content
         @ready = true
       end
     end