CI: Add building and testing actions (#8)

* working on build actions

* add test stage in actions

* removed two stages -- it runs too long

* change invoke to main

.github/workflows/build.yaml

@@ -0,0 +1,35 @@
+name: Build and Test with Mamba
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  build_and_test:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v3
+
+    - name: Set up Micromamba
+      uses: mamba-org/setup-micromamba@v1
+      with:
+        micromamba-version: 'latest'
+        environment-file: environment.yaml
+        init-shell: >-
+          bash
+        cache-environment: true
+        post-cleanup: 'all'
+
+    - name: Install dependencies
+      run: |
+        micromamba run -n mattersim pip install -e .
+
+    - name: Run tests
+      run: |
+        micromamba run -n mattersim pytest -s tests