Replace Travis CI with GitHub actions

.github/workflows/tests.yml

@@ -0,0 +1,36 @@
+name: Polysh Tests
+
+on:
+  push:
+    branches:
+      - '*'
+
+jobs:
+  polysh-tests:
+    name: python
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v3
+
+      - name: Set up Python
+        run: uv python install
+
+      - name: Install the project
+        run: uv sync --all-extras --dev
+
+      - name: Prepare test environment
+        run:
+          - sudo apt-get update
+          - sudo apt-get install -y openssh-server
+          - sudo service ssh start
+          - ssh-keygen -t ed25519 -N "" -f ~/.ssh/id_rsa
+          - cat ~/.ssh/id_ed25519.pub >> ~/.ssh/authorized_keys
+          - echo -e "Host *\n\tStrictHostKeyChecking no\n" >> ~/.ssh/config
+          - ssh -vvvv localhost exit
+
+      - name: Run tests
+        run: uv run python -m unittest discover --verbose