Speed up the lexer for Ruby 3.4+ (#1832)

* Speed up lexing

* Bump msrv to 3.0 (from 2.7)

* Normalize test for ruby-head compat

* Fix bug when parsing negative numbers

lib/liquid/parser.rb

@@ -53,7 +53,7 @@ module Liquid
         str = consume
         str << variable_lookups
       when :open_square
-        str = consume
+        str = consume.dup
         str << expression
         str << consume(:close_square)
         str << variable_lookups