chore: remove swiftsettings from bdk-swift

[reez]

Description

This removes the flag to suppress warnings on bdk-swift.

The motivation for this PR is to let bdk-swift work as a locally imported package, and work stably as a remote package.

Notes to the reviewers

We originally added this flag in PR 365 as the solution to the problem were bdk-swift users were getting many warnings in their project from bdk-swift. This was around the time of Xcode 13/14 and the correct solution.

However over the past few months I've seen a bunch of issues and weird behavior like in ldk-swift where the package would just error out, and being a blocker for anyone to even pull in the package I opened and resolved it; I didn't see that extreme of behavior in bdk-swift but kept monitoring it.

One bad behavior we did get in bdk-swift was if you were to use it as a local package Xcode wouldn't let you unless you commented it out this line of code manually, which is pretty frustrating and is why ldk-node just removed that code in a PR recently.

So my suggestion/solution for now its to remove it as well, and then monitor the situation to see if anything in Xcode changes that makes me feel comfortable if we put a fix in that it will remain stable.

An alternative solution is to put the line of code removed from bdk-ff Package.swift in the bdk-ffi Package.swift.txt, but at this point I’d rather wait on that since whatever change caused this in Xcode is not documented so they might keep changing things and potentially break whatever we fix.

Changelog notice

Checklists

All Submissions:

• I've signed all my commits
• I followed the contribution guidelines
• I ran cargo fmt and cargo clippy before committing

New Features:

• I've added tests for the new feature
• I've added docs for the new feature

Bugfixes:

• This pull request breaks the existing API
• I've added tests to reproduce the issue which are now passing
• I'm linking the issue being fixed by this PR

[thunderbiscuit]

ACK 6f4b4c9.