INFRAPRJ-7379: Add arm64 host builder. Part2.

Author: vbaskov-ledger

.github/workflows/speculos-builder.yml

@@ -21,10 +21,7 @@ on:
 jobs:
   build:
     name: Build and push speculos-builder image
-    strategy:
-      matrix:
-        label: [ubuntu-latest, speculos-builder-2c-arm64-ubuntu_2404]
-    runs-on: ${{ matrix.label }}
+    runs-on: ubuntu-latest
     permissions:
       packages: write
 
@@ -48,6 +45,7 @@ jobs:
     - name: Build and push speculos-builder to GitHub Packages
       uses: docker/build-push-action@v6
       with:
+        platforms: linux/amd64
         push: ${{ github.event_name == 'push' && github.ref == 'refs/heads/master' }}
         file: build.Dockerfile
         tags: ghcr.io/ledgerhq/speculos-builder:latest