add cache, switch to x64 build

.gitea/workflows/build.yaml

@@ -12,8 +12,15 @@ jobs:
         with:
           channel: master
 
+      - uses: actions/cache@v4
+        with:
+          path: /tmp/.buildx-cache
+          key: ${{ runner.os }}-buildx-${{ gitea.sha }}
+          restore-keys: |
+            ${{ runner.os }}-buildx-
+
       - name: Install Framework Dependencies
-        run: sudo apt-get update -y && sudo apt install -y ninja-build libgtk-3-dev
+        run: sudo apt-get update -y && sudo apt install -y ninja-build libgtk-3-dev x86_64-linux-gnu-gcc
 
       - name: Install Flutter
         uses: subosito/flutter-action@v2
@@ -31,4 +38,4 @@ jobs:
       #   run: flutter test
 
       - name: Build
-        run: flutter build linux
+        run: flutter build linux --target-platform linux-x64