Change requirements for `marcel`

[fatkodima]

Currently, the gem requires marcel up to the patch version, which I think is not needed and locks updates to that gem. It is better to lock up to the minor version or better just use >=.

[fatkodima]

@cgunther wdyt?

[cgunther]

I'm not a maintainer, just a fellow user. In theory, I'd agree with your proposal, the other dependencies are looser with >=.

[fatkodima]

Oops, was thinking you are a maintainer.