"flutter pub get" cannot resolve dependency of the latest "test" plugin 1.15.4

flutter_doctor.txt

[✓] Flutter (Channel stable, 1.22.0, on Mac OS X 10.15.5 19F101, locale en-US)
    • Flutter version 1.22.0 at /Users/suztomo/development/flutter
    • Framework revision d408d302e2 (7 days ago), 2020-09-29 11:49:17 -0700
    • Engine revision 5babba6c4d
    • Dart version 2.10.0

[✗] Android toolchain - develop for Android devices
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      Install Android Studio from: https://developer.android.com/studio/index.html
      On first launch it will assist you in installing the Android SDK components.
      (or visit https://flutter.dev/docs/get-started/install/macos#android-setup for detailed instructions).
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      You may also want to add it to your PATH environment variable.


[✓] Xcode - develop for iOS and macOS (Xcode 11.5)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 11.5, Build version 11E608c
    • CocoaPods version 1.9.1

[!] Android Studio (not installed)
    • Android Studio not found; download from https://developer.android.com/studio/index.html
      (or visit https://flutter.dev/docs/get-started/install/macos#android-setup for detailed instructions).

[✓] IntelliJ IDEA Community Edition (version 2020.2.1)
    • IntelliJ at /Applications/IntelliJ IDEA CE.app
    • Flutter plugin version 49.0.4
    • Dart plugin version 202.7206

[✓] VS Code
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.9.1

[✓] Connected device (1 available)
    • iPhone SE (mobile) • f77bfc37802a5ad50f67ef7ae673b7fbea699e7b • ios • iOS 13.4.1

! Doctor found issues in 2 categories.

flutter_pub_get_output.txt

~/Documents/test_conflict $ flutter pub get
Because test >=1.15.3 <1.16.0-nullsafety depends on test_api 0.2.18 and every version of flutter_test from sdk depends on test_api 0.2.19-nullsafety.2, test >=1.15.3 <1.16.0-nullsafety is incompatible with flutter_test from sdk.
So, because test_conflict depends on both flutter_test any from sdk and test 1.15.4, version solving failed.
Running "flutter pub get" in test_conflict...                           
pub get failed (1; So, because test_conflict depends on both flutter_test any from sdk and test
1.15.4, version solving failed.)

pubspec.yaml

name: test_conflict
description: A new Flutter project.

publish_to: 'none' # Remove this line if you wish to publish to pub.dev

environment:
  sdk: ">=2.7.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter

dev_dependencies:
  flutter_test:
    sdk: flutter
  # Latest is 1.15.4 as of Oct. 6th 2020
  test: 1.15.4