New `formatter`, 'suite-subtest-run', `suite-broken-parallel`!

What's Changed

• build(deps): bump golang.org/x/tools from 0.20.0 to 0.21.0 by @dependabot in #101
• build(deps): bump golangci/golangci-lint-action from 5 to 6 by @dependabot in #100
• New checker formatter by @Antonboom in #102
• contribution guideline: remove zero checker by @Antonboom in #103
• new checker 'suite-subtest-run' by @Antonboom in #104
• new checker suite-broken-parallel by @Antonboom in #118
• empty: added empty and zero length detection by @ccoVeille in #109

Full Changelog: v1.3.1...v1.4.0