Ruby 3.4.0 frozen string warnings

[hlascelles]

This gem mutates strings, which emits Warnings in ruby 3.4:

Here is a line where it happens: https://github.com/rollbar/rollbar-gem/blame/4694a35aba7518b30097a41fab15653d07cd73c0/lib/rollbar/middleware/js.rb#L126

gems/rollbar-3.4.1/lib/rollbar/middleware/js.rb:126: warning: literal string will be frozen in the future (run with --debug-frozen-string-literal for more information)

The gem should not mutate any strings. See https://blog.saeloun.com/2024/05/20/frozen-string-literal/

[linear]

SDK-519 Ruby 3.4.0 frozen string warnings