Drop Ruby 2.5 / 2.6 support #22

Job	Run time
Platform (windows-2022)	9m 2s
RuboCop	1m 32s
Unit tests on Windows with Ruby 3.2	1m 35s
Platform (ubuntu-22.04)	4m 13s
Platform (ubuntu-24.04)	4m 1s
Unit tests on Windows with Ruby 2.7	1m 45s
Integration on ubuntu-22.04 with Ruby 3.2	25s
Integration on windows-2022 with Ruby 2.7	2m 2s
Integration on windows-2022 with Ruby 3.2	1m 42s
Integration on ubuntu-latest with Ruby 2.7	37s
Integration on ubuntu-latest with Ruby jruby-9.4.8.0	3m 10s
Integration on ubuntu-latest with Ruby jruby-9.4.12.1	3m 13s
Unit tests on Linux with Ruby 3.2	16s
Unit tests on Linux with Ruby 2.7	32s
Unit tests on Linux with Ruby jruby-9.4.8.0	1m 20s
Unit tests on Linux with Ruby 3.0	16s
Unit tests on Linux with Ruby jruby-9.4.12.1	1m 18s
Unit tests on Linux with Ruby 3.4	17s
Unit tests on Linux with Ruby 4.0	14s
Unit tests on Linux with Ruby 3.3	18s
Test suite	2s
	37m 50s

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