CI: Install Python dependencies on Mac OS

Author: jonnor

.github/workflows/build.yaml

@@ -102,7 +102,8 @@ jobs:
         repository: jonnor/micropython
         path: micropython
         ref: v1.25.0    
-
+    - name: Install Python dependencies
+      run: pip install -r requirements.txt
     - name: Setup MicroPython X86
       working-directory: micropython
       run: |