Release v4.2.1

What's Changed

• fix(web-serial-rxjs): wait for fatal teardown before reconnect by @gurezo in #662
• fix(web-serial-rxjs): complete disconnect after connecting open closes by @gurezo in #663
• test(web-serial-rxjs): add strict consumer typecheck smoke by @gurezo in #664
• refactor(web-serial-rxjs): align operation cancelled severity by @gurezo in #665
• fix(web-serial-rxjs): snapshot send$ payload at subscribe by @gurezo in #666
• docs(web-serial-rxjs): document dispose$ subscribe requirement by @gurezo in #668
• chore(web-serial-rxjs): bump package version to 4.2.1 by @gurezo in #669

Full Changelog: v4.2.0...v4.2.1