CI: add configuration for running terminal emulator unit tests

.github/workflows/run_tests.yml

@@ -0,0 +1,13 @@
+name: Terminal unit tests
+
+on: push
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Clone repository
+      uses: actions/checkout@v2
+    - name: Execute tests
+      run: |
+        ./gradlew test