Use GitHub Actions (Windows) (#254)

Author: kubawerlos

.gitattributes

@@ -2,3 +2,5 @@
 /tests/ export-ignore
 /.* export-ignore
 /phpunit.xml export-ignore
+
+* text eol=lf

.github/workflows/ci.yml

@@ -25,7 +25,7 @@ jobs:
  test:
  strategy:
  matrix:
- os: [macos-latest, ubuntu-latest]
+ os: [macos-latest, ubuntu-latest, windows-latest]
  php-version: ['7.4']
  include:
  - os: ubuntu-latest