Update build_esp32.yml

Try to use the espressif idf 4.4 container for running the build

Author: mocleiri

.github/workflows/build_esp32.yml

@@ -12,8 +12,9 @@ on:
 
 jobs:
   tensorflow_micropython_esp32_build:
-    runs-on: espressif/idf:release-v4.4
-
+    runs-on: ubuntu-latest
+    container:
+      image: espressif/idf:release-v4.4
     steps:
       - name: Checkout repository
         uses: actions/checkout@v2