use from instead of branch for swift docc plugin

Author: sebsto

Package.swift

@@ -13,7 +13,7 @@ let package = Package(
         .package(url: "https://github.com/apple/swift-openapi-runtime.git", from: "1.0.0"),
         .package(url: "https://github.com/swift-server/swift-aws-lambda-runtime.git", from: "1.0.0-alpha.1"),
         .package(url: "https://github.com/swift-server/swift-aws-lambda-events.git", from: "0.1.0"),
-        .package(url: "https://github.com/apple/swift-docc-plugin", branch: "main"),
+        .package(url: "https://github.com/apple/swift-docc-plugin", from: "1.3.0"),
     ],
     targets: [
         .target(