replaced bitbucket CI with github CI

Author: Jaroslav S

.github/workflows/ci.yml

@@ -0,0 +1,21 @@
+name: CI
+
+on: [push]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: '8.5'
+          coverage: none
+
+      - name: Install dependencies
+        uses: ramsey/composer-install@v3
+
+      - name: Run tests
+        run: make test