auto sync master and master-v2

[boolafish]

Probably reuse the GH action setup in plasma-contracts and plasma-contract-private

[souradeep-das]

What should be the ideal way to merge into master-v2?

If we squash-and-merge the commits apparently add up every-time (since there is no reference to this older commits on master-v2)

For instance, the successive pull requests will look like this-

1st PR

2nd PR

3rd PR