Add v5 package manifest.

Alamofire.xcodeproj/project.pbxproj

@@ -289,6 +289,7 @@
 		312D1E0C1FC2551400E51FF1 /* AdvancedUsage.md */ = {isa = PBXFileReference; lastKnownFileType = net.daringfireball.markdown; name = AdvancedUsage.md; path = Documentation/AdvancedUsage.md; sourceTree = "<group>"; };
 		316250E41F00ABE900E207A6 /* ISSUE_TEMPLATE.md */ = {isa = PBXFileReference; lastKnownFileType = net.daringfireball.markdown; name = ISSUE_TEMPLATE.md; path = .github/ISSUE_TEMPLATE.md; sourceTree = "<group>"; };
 		316250E51F00ACD000E207A6 /* PULL_REQUEST_TEMPLATE.md */ = {isa = PBXFileReference; lastKnownFileType = net.daringfireball.markdown; name = PULL_REQUEST_TEMPLATE.md; path = .github/PULL_REQUEST_TEMPLATE.md; sourceTree = "<group>"; };
+		3173BF5A231F5A37009F98C2 /* Package@swift-4.2.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Package@swift-4.2.swift"; sourceTree = "<group>"; };
 		31B2CA9421AA24F5005B371A /* Package@swift-4.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Package@swift-4.swift"; sourceTree = "<group>"; };
 		31B2CA9521AA25CD005B371A /* Package.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Package.swift; sourceTree = "<group>"; };
 		31ED52E61D73889D00199085 /* AFError+AlamofireTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = "AFError+AlamofireTests.swift"; sourceTree = "<group>"; };
@@ -650,6 +651,7 @@
 				4CE292391EF4B12B008DA555 /* Alamofire.podspec */,
 				4CF3B4281F5FC7900075BE59 /* LICENSE */,
 				31B2CA9521AA25CD005B371A /* Package.swift */,
+				3173BF5A231F5A37009F98C2 /* Package@swift-4.2.swift */,
 				31B2CA9421AA24F5005B371A /* Package@swift-4.swift */,
 				4CE2923A1EF4B12B008DA555 /* Package@swift-3.swift */,
 			);

Package.swift

-// swift-tools-version:4.2
+// swift-tools-version:5.0
 //
 //  Package.swift
 //
@@ -37,5 +37,5 @@ let package = Package(
             name: "Alamofire",
             path: "Source")
     ],
-    swiftLanguageVersions: [.v3, .v4, .v5]
+    swiftLanguageVersions: [.v4, .v5]
 )

Package@swift-4.2.swift

+// swift-tools-version:4.2
+//
+//  Package.swift
+//
+//  Copyright (c) 2014 Alamofire Software Foundation (http://alamofire.org/)
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+import PackageDescription
+
+let package = Package(
+    name: "Alamofire",
+    products: [
+        .library(
+            name: "Alamofire",
+            targets: ["Alamofire"])
+    ],
+    targets: [
+        .target(
+            name: "Alamofire",
+            path: "Source")
+    ],
+    swiftLanguageVersions: [.v3, .v4]
+)