workflows: test on windows as well

.github/workflows/tests.yml

@@ -4,7 +4,8 @@ on: [push, pull_request]
 
 jobs:
 
-  phpunit:
+  linux:
+    name: Test on Linux
     runs-on: ubuntu-18.04
     strategy:
       fail-fast: false
@@ -22,6 +23,37 @@ jobs:
       - run: composer install --no-progress
       - run: php${{ matrix.php-version }} vendor/bin/phpunit
 
+  windows:
+    name: Test on Windows
+    defaults:
+      run:
+        shell: cmd
+    runs-on: windows-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        php-version: ['7.3', '7.4', '8.0', '8.1']
+        arch: [x64]
+        ts: [nts]
+
+    steps:
+      - name: Setup PHP
+        id: setup-php
+        uses: cmb69/setup-php-sdk@v0.1
+        with:
+          version: ${{matrix.php-version}}
+          arch: ${{matrix.arch}}
+          ts: ${{matrix.ts}}
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 1
+
+      - run: php -v
+      - run: php -m
+      - run: composer -V
+      - run: composer install --no-progress
+      - run: php -dextension=gd vendor/bin/phpunit
+
   code_coverage:
     name: Code Coverage
     runs-on: ubuntu-latest