Update build_esp32.yml

Try to fix build problem by building on the espressif idf 4.4 container directly.

.github/workflows/build_esp32.yml

@@ -12,7 +12,7 @@ on:
 
 jobs:
   tensorflow_micropython_esp32_build:
-    runs-on: ubuntu-latest
+    runs-on: espressif/idf:release-v4.4
 
     steps:
       - name: Checkout repository