Use SwiftPM to run swift-format

.gitignore

@@ -1,5 +1,6 @@
 .DS_Store
 /.build
 /Packages
+/Tools/.build
 /*.xcodeproj
 swift-format/

Captain.config.json

@@ -1,7 +1,7 @@
 {
     "pre-commit": [
-        "swift run --package-path swift-format swift-format -r Sources -i",
-        "swift run --package-path swift-format swift-format -r Tests -i",
+        "swift run --package-path Tools swift-format -r Sources -i",
+        "swift run --package-path Tools swift-format -r Tests -i",
         "git add ."
      ]
 }

Scripts/init.sh

@@ -1,4 +1,3 @@
 #!/bin/bash
-git clone [email protected]:apple/swift-format.git swift-format
 swift run captain uninstall
 swift run captain install

Tools/Package.resolved

@@ -0,0 +1,34 @@
+{
+  "object": {
+    "pins": [
+      {
+        "package": "swift-format",
+        "repositoryURL": "https://github.com/apple/swift-format",
+        "state": {
+          "branch": "master",
+          "revision": "0266e971d63a48148ab9d55bb4559dc23f974033",
+          "version": null
+        }
+      },
+      {
+        "package": "SwiftSyntax",
+        "repositoryURL": "https://github.com/apple/swift-syntax",
+        "state": {
+          "branch": "swift-DEVELOPMENT-SNAPSHOT-2020-01-29-a",
+          "revision": "16f6af54d9ad3cfcb35cd557288783dded1107fd",
+          "version": null
+        }
+      },
+      {
+        "package": "swift-tools-support-core",
+        "repositoryURL": "https://github.com/apple/swift-tools-support-core.git",
+        "state": {
+          "branch": null,
+          "revision": "693aba4c4c9dcc4767cc853a0dd38bf90ad8c258",
+          "version": "0.0.1"
+        }
+      }
+    ]
+  },
+  "version": 1
+}

Tools/Package.swift

@@ -0,0 +1,9 @@
+// swift-tools-version:5.1
+import PackageDescription
+
+let package = Package(
+    name: "Tools",
+    dependencies: [
+        .package(url: "https://github.com/apple/swift-format", .branch("master"))
+    ]
+)