Reader: Use SwiftUIPager 2.0.

[Rawgers]

SwiftUIPager has a new update as of January 15, 2021 (Version 2.0). It replaces its binding-based init with one that takes an optional @StateObject for the initial page. As this is a breaking change for us, we have frozen the SwiftUIPager version to 1.14.1. We would like to update to Version 2.0 if possible because the update reportedly makes the Pager move more smoothly (some preliminary testing does seem to have this improvement).