Integrate the new SwiftPM `add-dependency` command in the "Use this package" modal

[daveverwer]

Discussed in https://github.com/SwiftPackageIndex/SwiftPackageIndex-Server/discussions/3188

^{Originally posted by **MahdiBM** July 5, 2024} We have a new `add-dependency` command in Swift 6: ```bash swift package add-dependency https://github.com/DiscordBM/DiscordBM --from 1.12.0 ``` SPI's "Use this package" view should include this, with a small note that it requires Swift 6 CLI. crates.io also references these commands, which reminded me that we recently got them in Swift too, so SPI can also do that: