Upgrade rdkafka ~> 0.15; require Ruby 3.0 since 2.6 is EOL

[tednology]

What

This PR completes a couple of housekeeping items:

1. Set required Ruby to >= 3.0 in the Gemspec (2.6 is EOL, 2.7 support dropping in rdkafka-ruby soon, too)
2. Upgrade rdkafka to ~> 0.15.0

I noticed that rdkafka 0.15.0 minimum Ruby is 2.7 anyway.

[mensfeld]

@tednology you might as well directly go to 3.0 because I am dropping support for 2.7 soon: karafka/rdkafka-ruby#374

[tednology]

@mensfeld Done.

[mensfeld]

No need to ping me. It's not my framework and I don't have merge permissions here ;) it was just a friendly advise from rdkafka maintainer.

[tednology]

Hah, well, thanks anyway 😄.

@deepredsky or @dasch, sorry for the ping, would it be possible to review this small upgrade? We don't need the minimum Ruby version requirement @ 3.0 (2.7 will suffice) if it's a concern.

[deepredsky]

@tednology thanks for this pull request. I need to double check that upgrading rdkafka will not require any additional changes. +1 to dropping 2.6 support

[mensfeld]

@deepredsky it will not. 0.15.0 is fully backwards compatible with 0.13 though I did change several timeouts to higher values.

[deepredsky]

@tednology can u add a changelog entry and also fixup the commit about lockfile. I will release a new beta with this tomorrow

[tednology]

You bet!

[jandudulski]

@deepredsky can you please release a new beta with this change? 🙏

[deepredsky]

@deepredsky can you please release a new beta with this change? 🙏

hi @jandudulski new beta is released. Also wanted to mention that you don't have to wait for beta versions to be released to use in ur project, you can use bundler's git feature to test the unreleased changes :)

[jandudulski]

Thank you @deepredsky . Unfortunately, I have to bump it in another lib that is built on top of racecar, and this makes things a little bit more complicated to test 😀