ci: Use shallow LiteX setup clones

Use litex_setup.py --clone-depth=1 in CI to reduce clone time and network usage.

litex_setup keeps full clones for repositories that need pinned tag/SHA1 checkouts, so pinned CPU/pythondata repositories remain compatible.

Author: enjoy-digital

.github/workflows/ci.yml

@@ -66,7 +66,7 @@ jobs:
       - name: Install LiteX
         run: |
           wget https://raw.githubusercontent.com/enjoy-digital/litex/master/litex_setup.py
-          python3 litex_setup.py init install --user
+          python3 litex_setup.py --clone-depth=1 init install --user
 
       # Install Project
       - name: Install Project