Gem version too constrained?

[inopinatus]

https://github.com/wildbit/postmark-rails/blob/ebfe891f2b16631338d0dee7e858b3510e88d348/postmark-rails.gemspec#L24

Any reason why this can't be "~> 1.15" (meaning "any version 1.x from 1.15 or later, but less than 2.x")? As written, it's "~> 1.15.0" which means "any 1.15.x, but not 1.16.0 or later".

That's inhibiting update of the main postmark gem to 1.19.0. Assuming the gems are using semantic versioning, 1.19.0 would be backwards compatible with 1.15.0.