Make strict concurrency flags enableable

Package.swift

@@ -27,20 +27,20 @@ let swiftSystem: PackageDescription.Target.Dependency = .product(
  condition: .when(platforms: [.macOS, .iOS, .tvOS, .watchOS, .linux, .android])
 )
 
+let strictConcurrencyDevelopment = false
+
 let strictConcurrencySettings: [SwiftSetting] = {
  var initialSettings: [SwiftSetting] = []
  initialSettings.append(contentsOf: [
  .enableUpcomingFeature("StrictConcurrency"),
  .enableUpcomingFeature("InferSendableFromCaptures"),
  ])
 
- #if compiler(>=6.0)
- if ProcessInfo.processInfo.environment["CI"] != nil {
+ if strictConcurrencyDevelopment {
  // -warnings-as-errors here is a workaround so that IDE-based development can
  // get tripped up on -require-explicit-sendable.
  initialSettings.append(.unsafeFlags(["-require-explicit-sendable", "-warnings-as-errors"]))
  }
- #endif
 
  return initialSettings
 }()