fix forgejo workflows to use proper syntax without external actions

.forgejo/workflows/build.yml

@@ -12,17 +12,18 @@ jobs:
     
     steps:
     - name: Checkout code
-      uses: actions/checkout@v4
+      run: |
+        git clone ${{ github.server_url }}/${{ github.repository }} .
+        git checkout ${{ github.sha }}
       
     - name: Set up Python
-      uses: actions/setup-python@v4
-      with:
-        python-version: '3.12'
+      run: |
+        sudo apt update
+        sudo apt install -y python3.12 python3.12-venv python3-pip
         
     - name: Install system dependencies
       run: |
-        sudo apt update
-        sudo apt install -y sbuild schroot debootstrap python3-venv python3-pip
+        sudo apt install -y sbuild schroot debootstrap
         
     - name: Create deb-mock directories
       run: |
@@ -56,14 +57,9 @@ jobs:
         source venv/bin/activate
         python setup.py sdist bdist_wheel
         
-    - name: Upload build artifacts
-      uses: actions/upload-artifact@v3
-      with:
-        name: deb-mock-package
-        path: dist/
-        
-    - name: Upload coverage reports
-      uses: actions/upload-artifact@v3
-      with:
-        name: coverage-reports
-        path: coverage.xml 
+    - name: List artifacts
+      run: |
+        echo "Build artifacts created:"
+        ls -la dist/
+        echo "Coverage report:"
+        ls -la coverage.xml