chore(packaging): bump version to 2.0.0-alpha.28

chore(release): releases 2.0.0-alpha.27

chore(release): releases alpha.26

chore(release): bump version to alpha.25

chore(packaging): bump version to 2.0.0-alpha.24

chore(publishing): fix pubspec authors field

chore(release): releases alpha.22

chore(packaging): bump version to 2.0.0-alpha.21; add changelog

chore(packaging): bump version to 2.0.0-alpha.20

chore(packaging): bump version to 2.0.0-alpha.19