fix: update Makefile to copy third party libraries recursively

[lucasmpaim]

When using install with homebrew we got this error:

Last 15 lines from /Users/lucaspaim/Library/Logs/Homebrew/danger-swift/01.make:
[5/10] Compiling RunnerLib CliArgs.swift
[6/10] Compiling DangerDependenciesResolver Data+Encoding.swift
[7/11] Compiling Runner Edit.swift
[8/11] Linking danger-swift
[9/11] Compiling OctoKit Configuration.swift
[10/12] Compiling Danger BitBucketCloud.swift
[11/13] Linking libDanger.dylib
[12/13] Compiling DangerFixtures CustomGitHubDSL.swift
[13/13] Linking libDangerFixtures.dylib
mkdir -p /usr/local/Cellar/danger-swift/3.2.0/bin
mkdir -p /usr/local/Cellar/danger-swift/3.2.0/lib/danger
cp -f .build/release/danger-swift /usr/local/Cellar/danger-swift/3.2.0/bin/danger-swift
cp -f .build/release/libDanger.* .build/release/Danger.swiftdoc .build/release/Danger.swiftmodule .build/release/OctoKit.swiftdoc .build/release/OctoKit.swiftmodule .build/release/RequestKit.swiftdoc .build/release/RequestKit.swiftmodule .build/release/Logger.swiftdoc .build/release/Logger.swiftmodule .build/release/DangerShellExecutor.swiftdoc .build/release/DangerShellExecutor.swiftmodule /usr/local/Cellar/danger-swift/3.2.0/lib/danger
cp: .build/release/libDanger.dylib.dSYM is a directory (not copied).
make: *** [install] Error 1

This PR fixes it

[orta]

Cool, this makes sense to me - I wonder what changed to make it need to happen

[f-meloni]

I think is changed how OSX threats them, from Catalina

[peril-staging]

Thanks for the PR @lucasmpaim.

This PR has been shipped in v3.2.1 - CHANGELOG.