added github test action

.github/workflows/tests.yml

@@ -0,0 +1,33 @@
+# This is tests workflow for GitHub Actions
+
+name: Tests
+
+on:
+  push:
+    branches: [ master, develop ]
+  pull_request:
+    branches: [ master, develop ]
+
+jobs:
+  build:
+    runs-on: ubuntu-18.04
+    steps:
+    # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
+    - uses: actions/checkout@v2
+
+    - name: prepare for Docker image build
+      run: |
+        cp ./extras/docker/Dockerfile ./
+        cp ./extras/docker/.dockerignore ./
+
+    - name: build Docker image
+      run: docker build -t andresriancho/w3af:test-action
+
+
+  test:
+    runs-on: ubuntu-18.04
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: run w3af tests
+      run: docker run -it andresriancho/w3af:test-action pytest