gh-actions: install deps

Author: nschloe

.github/workflows/build.yml

@@ -27,13 +27,20 @@ jobs:
       with:
         python-version: "3.x"
     - uses: actions/checkout@v1
+    - name: Install dependencies
+      run: sudo apt-get install -y texlive-latex-base texlive-latex-extra python3-tk python3-scipy
     - name: Install package
       run: |
         pip install --upgrade pip
         pip install .
+    - name: Extract tests from README
+      run: |
+        pip install excode
+        excode README.md test/zzz_readme_test.py --filter python,test
     - name: Test with pytest
       run: |
         pip install pytest pytest-cov
-        pytest --cov tikzplotlib
+        pip install -r test_requirements.txt
+        MPLBACKEND=Agg pytest --cov tikzplotlib
     - name: Submit to codecov
       run: bash <(curl -s https://codecov.io/bash) -R ~/work