tomcat@9: rename from tomcat

Aliases/tomcat@9

@@ -1 +0,0 @@
-../Formula/tomcat.rb

Formula/tomcat@9.rb

@@ -1,4 +1,4 @@
-class Tomcat < Formula
+class TomcatAT9 < Formula
   desc "Implementation of Java Servlet and JavaServer Pages"
   homepage "https://tomcat.apache.org/"
   url "https://www.apache.org/dyn/closer.lua?path=tomcat/tomcat-9/v9.0.43/bin/apache-tomcat-9.0.43.tar.gz"
@@ -6,8 +6,14 @@ class Tomcat < Formula
   sha256 "30703af07182c3c815a7e44376939b69da406ab64bd6f9c5ced9c455ad013a1b"
   license "Apache-2.0"
 
+  livecheck do
+    url :stable
+  end
+
   bottle :unneeded
 
+  keg_only :versioned_formula
+
   depends_on "openjdk"
 
   def install