Change arm64 flatpak to build barebones, rather than through emulation

This new addition is highlighted in GitHub's new blog post: 
https://github.blog/changelog/2025-01-16-linux-arm64-hosted-runners-now-available-for-free-in-public-repositories-public-preview/

.github/workflows/build_all.yml

@@ -62,8 +62,15 @@ jobs:
     secrets: inherit
   flatpak:
     name: "Flatpak"
-    runs-on: ubuntu-latest
-    timeout-minutes: 600
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        include: 
+          - os: ubuntu-latest
+            arch: x86_64
+          - os: ubuntu-latest
+            arch: arm64
+      fail-fast: false
     env:
       date:
       ver:
@@ -76,10 +83,6 @@ jobs:
         - /usr/share/dotnet:/usr/share/dotnet
         - /opt/ghc:/opt/ghc1
         - /usr/local/share/boost:/usr/local/share/boost1
-    strategy:
-      matrix:
-        arch: [x86_64, aarch64]
-      fail-fast: false
     steps:
     - name: "Remove unneeded stuff to free disk space"
       run:
@@ -97,16 +100,6 @@ jobs:
         echo "ver_pure=$ver_pure" >> $GITHUB_ENV
         echo "date=$(date +'%Y%m%d')" >> $GITHUB_ENV
       shell: bash
-    - name: Install deps
-      if: ${{ matrix.arch != 'x86_64' }}
-      run: |
-        dnf -y install docker
-    - name: Set up QEMU
-      if: ${{ matrix.arch != 'x86_64' }}
-      id: qemu
-      uses: docker/setup-qemu-action@v2
-      with:
-        platforms: arm64
     - uses: flatpak/flatpak-github-actions/flatpak-builder@v6
       with:
         bundle: OrcaSlicer-Linux-flatpak_${{ env.ver }}.flatpak