java_requirement.rb: use HTTPS in Java Platform URL

It's redirected to cleartext, though this URL will be opened
in a browser so it won't be something hidden, and maybe
Oracle will fix this in the future.

Library/Homebrew/requirements/java_requirement.rb

@@ -2,7 +2,7 @@ require "language/java"
 
 class JavaRequirement < Requirement
   fatal true
-  download "http://www.oracle.com/technetwork/java/javase/downloads/index.html"
+  download "https://www.oracle.com/technetwork/java/javase/downloads/index.html"
 
   satisfy build_env: false do
     setup_java