Try to resolve docker push take 1337

Trying a recommended setting from @imranzunzani mentioned here: moby/buildkit#3969
Also reverted back to ubuntu-latest.

.github/workflows/rust-musl.yml

@@ -46,7 +46,7 @@ name: Rust MUSL
 jobs:
   build_vars:
     name: Generate Build Variables
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     outputs:
       current_date: ${{ steps.build_vars.outputs.current_date }}
       nightly_date: ${{ steps.build_vars.outputs.nightly_date }}
@@ -180,7 +180,7 @@ jobs:
   musl-base:
     name: Build MUSL Base Image - ${{ matrix.env.IMAGE_TAG }} - (OpenSSL v${{ matrix.openssl_version }})
     needs: [build_vars]
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     env:
       HAVE_DOCKERHUB_LOGIN: ${{ secrets.DOCKERHUB_USERNAME != '' && secrets.DOCKERHUB_TOKEN != '' }}
       HAVE_GHCR_LOGIN: ${{ github.repository_owner != '' && secrets.GITHUB_TOKEN != '' }}
@@ -224,10 +224,10 @@ jobs:
       - name: Setup Docker Buildx (setup-buildx-action)
         if: ${{ !env.ACT }}
         uses: docker/setup-buildx-action@ecf95283f03858871ff00b787d79c419715afc34 # v2.7.0
-        # https://github.com/docker/build-push-action/issues/761#issuecomment-1383822381
-        # with:
-        #   driver-opts: |
-        #     image=moby/buildkit:v0.10.6
+        # https://github.com/moby/buildkit/issues/3969
+        with:
+          driver-opts: |
+            network=host
 
       # Use the DOCKER_BUILDKIT=1 env when using `act`
       - name: Setup Docker Buildx (DOCKER_BUILDKIT=1)