Speed up code samples workflow

Author: mnocon

.github/workflows/code_samples.yaml

@@ -100,7 +100,7 @@ jobs:
             -   name: Log target branch code_samples usage
                 if: steps.list.outputs.CODE_SAMPLES_CHANGE != ''
                 run: |
-                    git fetch origin
+                    git fetch origin --depth=1 ${{ github.head_ref }}
                     git checkout origin/${{ github.head_ref }} -- tools/code_samples/code_samples_usage.php
                     php tools/code_samples/code_samples_usage.php ${{ steps.list.outputs.CODE_SAMPLES_CHANGE }} > $HOME/code_samples_usage_target.txt