Update XcodeEdit dependency

Package.resolved

@@ -24,8 +24,8 @@
         "repositoryURL": "https://github.com/tomlokhorst/XcodeEdit",
         "state": {
           "branch": null,
-          "revision": "6cf2916aac748b9a687c2bfd1ef27d2adb70453b",
-          "version": "2.6.0"
+          "revision": "1af368143ca4843136df5b3945f2cc3c49b980e0",
+          "version": "2.7.1"
         }
       }
     ]

Package.swift

@@ -1,11 +1,14 @@
-// swift-tools-version:4.2
+// swift-tools-version:5.0
 import PackageDescription
 
 let package = Package(
   name: "rswift",
+  platforms: [
+    .macOS(.v10_11)
+  ],
   dependencies: [
     .package(url: "https://github.com/kylef/Commander.git", from: "0.8.0"),
-    .package(url: "https://github.com/tomlokhorst/XcodeEdit", from: "2.5.0")
+    .package(url: "https://github.com/tomlokhorst/XcodeEdit", from: "2.7.0")
   ],
   targets: [
     .target(

README.md

@@ -124,7 +124,7 @@ _Tip:_ Add the `*.generated.swift` pattern to your `.gitignore` file to prevent
 R.swift is built using [Swift Package Manager (SPM)](https://github.com/apple/swift-package-manager).
 
 1. Check out the code
-2. Run `swift build -c release -Xswiftc -static-stdlib -Xswiftc "-target" -Xswiftc "x86_64-apple-macosx10.11"` from the root directory
+2. Run `swift build -c release` from the root directory
 3. Follow the manual installation steps with the binary you now have
 
 For developing on R.swift in Xcode, run `swift package generate-xcodeproj --xcconfig-overrides RswiftConfig.xcconfig`.