Swift 6.1 Release

What's Changed

• [build] Use C++17 standard by @egorzhdan in #20
• [build] Require Swift 5.9 or newer by @egorzhdan in #21
• [LLVM] Fix compilation with Swift 5.9 or newer by @egorzhdan in #22
• [LLVM] Add conversion from StringRef to std::string by @egorzhdan in #23
• [build] Add a Swift Package manifest by @egorzhdan in #24
• [build] Fix C++ interop flag deprecation warning by @egorzhdan in #25
• Remove uses of fatalError from Package.swift by @MaxDesiatov in #26
• [build] Prevent CMake from de-duplicating compiler options by @egorzhdan in #27
• [LLVM] Add API Notes for LLVM_Utils by @egorzhdan in #29
• [build] Fix LLVM module map location #30 by @FlickerSoul in #31
• [Clang] Add API Notes for Clang_AST by @egorzhdan in #34
• Update readme with the Swift version requirement by @egorzhdan in #35
• Delete CONTRIBUTING.md by @parispittman in #36
• Delete CODE_OF_CONDUCT.md by @parispittman in #37
• Update readme after the migration to swiftlang org by @egorzhdan in #38

New Contributors

• @FlickerSoul made their first contribution in #31
• @parispittman made their first contribution in #36

Full Changelog: swift-6.0.3-RELEASE...swift-6.1-RELEASE