Add v0.3.0-backport for ci

Merge pull request #351 from maticnetwork/pre-upgrade-fixes

Pre upgrade fixes

Merge pull request #349 from maticnetwork/missing-test

new: migration case when validator unstaked

Merge pull request #347 from maticnetwork/fix-proposer-bonus

Fix proposer bonus

Merge pull request #345 from maticnetwork/pre-upgrade

Pre upgrade

Merge pull request #343 from maticnetwork/missing-rewards

Adjust rewards for missed checkpoints.

Merge pull request #315 from maticnetwork/mat-1927

overriden owner in upgradable proxy (mat-1980)

Merge pull request #333 from maticnetwork/migrate-delegation

Migrate delegation

0.3.2

0.3.1