Release v0.6.4+cdk.6

Release v0.6.4+cdk.5

safe mode by default (0xPolygon#3547)

* safe mode by default

* doc

Feature/0xPolygon#3544 sync block protection (0xPolygon#3545)

* SyncBlockProtection parameter

* linter

* config

* Fix unit test

Stop syncing l1inforoot when invalid l1inforoot is detected (0xPolygo…

…n#3542)

* stop syncing l1inforoot when invalid l1inforoot is detected

* fix linter

Merge pull request 0xPolygon#120 from 0xPolygon/fork9/#3544_syncBlock…

…Protection

Add sync block protection