fix: add cython to build pysimdjson

.github/workflows/test.yml

@@ -26,7 +26,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install -r requirements.txt pytest
+        pip install -r requirements.txt pytest cython
         pip install -e .
     - name: Test with pytest
       run: |