Update to Ruby 3

[amotl]

Hi there,

apparently, this repository is still on Ruby 2.

activerecord-crate-adapter/.github/workflows/tests.yml

Lines 26 to 28 in f58fe3e

	matrix:
	os: [ "ubuntu-latest" ]
	ruby-version: [ "2.4", "2.5", "2.6" ]

Coming from https://www.ruby-lang.org/en/downloads/releases/, I think it is safe to assume Ruby 2 is a thing of the past, and the repository should be upgraded to work with recent versions of Ruby 3? wdyt, @hammerhead?

With kind regards,
Andreas.

NB: This may also help to make GH-26 conclude without needing to bring in old Bundler releases still working on Ruby 2 in one way or another.

[hammerhead]

Hi,

Yes, upgrading to Ruby 3 totally makes sense. I think the currently used activerecord version doesn't support Ruby 3 yet, so we need to upgrade to a (slightly) more recent activerecord version first, before bumping Ruby itself.

Just opened #29 to at least fix the build right now on 2.7.

[amotl]

Thanks. Let me also cite your other discovery here:

The usage of BigDecimal.new within activerecord itself currently blocks further Ruby version upgrades. As per that link above, Ruby 2.7 is the latest version still supporting BigDecimal.new.

-- #29 (comment)