Enable remaining soundness checks

.github/workflows/pull_request.yml

@@ -25,8 +25,3 @@ jobs:
   soundness:
     name: Soundness
     uses: swiftlang/github-workflows/.github/workflows/soundness.yml@main
-    with:
-      license_header_check_project_name: "Swift.org"
-      license_header_check_enabled: false
-      # https://github.com/apple/swift-algorithms/issues/251
-      docs_check_enabled: false

.license_header_template

@@ -0,0 +1,10 @@
+@@===----------------------------------------------------------------------===@@
+@@
+@@ This source file is part of the Swift Algorithms open source project
+@@
+@@ Copyright (c) YEARS Apple Inc. and the Swift project authors
+@@ Licensed under Apache License v2.0 with Runtime Library Exception
+@@
+@@ See https://swift.org/LICENSE.txt for license information
+@@
+@@===----------------------------------------------------------------------===@@

.licenseignore

@@ -0,0 +1,30 @@
+.gitignore
+**/.gitignore
+.licenseignore
+.gitattributes
+.git-blame-ignore-revs
+.mailfilter
+.mailmap
+.spi.yml
+.swift-format
+.editorconfig
+.github/*
+*.md
+*.mdoc
+*.txt
+*.yml
+*.yaml
+*.json
+*.png
+*.bash
+*.cmake
+*.cmake.in
+Package.swift
+**/Package.swift
+Package@*.swift
+**/Package@*.swift
+Package.resolved
+**/Package.resolved
+.unacceptablelanguageignore
+**/Snapshots/*
+Xcode/*

Sources/Algorithms/Trim.swift

@@ -7,6 +7,7 @@
 //
 // See https://swift.org/LICENSE.txt for license information
 //
+//===----------------------------------------------------------------------===//
 
 //===----------------------------------------------------------------------===//
 // trimmingPrefix(while:)