Bump to Swift 6.1 toolchain

Author: Kyle-Ye

.github/workflows/compatibility_tests.yml

@@ -14,7 +14,7 @@ jobs:
       matrix:
         include:
           - os: macos-15
-            xcode-version: "16.0"   # Swift 6.0
+            xcode-version: "16.3"   # Swift 6.1
     runs-on: ${{ matrix.os }}
     env:
       OPENGRAPH_WERROR: 1

.github/workflows/ios.yml

@@ -13,7 +13,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [macos-15]
-        xcode-version: ["16.0"]   # Swift 6.0
+        xcode-version: ["16.3"]   # Swift 6.1
         ios-version: ["18.0"]
         include:
           - ios-version: "18.0"

.github/workflows/macos.yml

@@ -13,7 +13,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [macos-15]
-        xcode-version: ["16.0"]   # Swift 6.0
+        xcode-version: ["16.3"]   # Swift 6.1
     runs-on: ${{ matrix.os }}
     env:
       OPENGRAPH_WERROR: 1

.github/workflows/ubuntu.yml

@@ -12,7 +12,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        swift_version: ["6.0"]
+        swift_version: ["6.1"]
     runs-on: ubuntu-22.04
     env:
       OPENGRAPH_WERROR: 1

Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version: 6.0
+// swift-tools-version: 6.1
 // The swift-tools-version declares the minimum version of Swift required to build this package.
 
 import Foundation

README.md

@@ -25,6 +25,10 @@ The project is for the following purposes:
 
 Currently, this project is in early development.
 
+## Build
+
+The current suggested toolchain to build the project is Swift 6.1 / Xcode 16.3.
+
 ## Credits
 
 OpenGraph_SPI's Data, Graph, Vector and more is modified based on [Compute](https://github.com/jcmosc/Compute)'s implementations.