Add GitHub CI workflow

.github/workflows/build.yml

@@ -0,0 +1,19 @@
+name: Build
+
+on: [push]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v1
+    - name: Set up Python 3.8
+      uses: actions/setup-python@v1
+      with:
+        python-version: 3.8
+    - name: Install dependencies
+      run: pip install -r dev-requirements.txt
+    - name: Run tests
+      run: bash ./scripts/test.sh

README.md

@@ -1,2 +1,5 @@
 # todoist-github
+
+![](https://github.com/RealOrangeOne/todoist-github/workflows/Build/badge.svg)
+
 Import assigned issues and PRs into Todoist