[ruby/irb] Version 1.5.0

Asked by ko1 to release https://github.com/ruby/irb/pull/444 for
simplifying https://github.com/ruby/debug/pull/808,
and hsbt made me a gem owner for this.

Stan said 1.4.3 should have been 1.5.0, but now that it's already
released and it's not worth yanking it, we're not doing that change.
However, now that this release includes `debug` and `edit`, I think it's
a good opportunity to hit the version 1.5.0.

https://github.com/ruby/irb/commit/85937d71f6

lib/irb/version.rb

@@ -11,7 +11,7 @@
 #
 
 module IRB # :nodoc:
-  VERSION = "1.4.3"
+  VERSION = "1.5.0"
   @RELEASE_VERSION = VERSION
-  @LAST_UPDATE_DATE = "2022-11-17"
+  @LAST_UPDATE_DATE = "2022-11-20"
 end