manifest update: don't clean on checkout

.github/workflows/manifest.yml

@@ -41,6 +41,7 @@ jobs:
         uses: actions/checkout@v3
         with:
           ref: 'main'
+          clean: false
       - name: Generate manifest and shields for main branch
         run: python imgen.py shields
       - name: Save main's manifest
@@ -51,6 +52,7 @@ jobs:
         uses: actions/checkout@v3
         with:
           ref: 'latest'
+          clean: false
       - name: Generate manifest for latest
         run: python imgen.py
       - name: Save latest's manifest
@@ -61,6 +63,7 @@ jobs:
         uses: actions/checkout@v3
         with:
           ref: 'devel'
+          clean: false
       - name: Generate manifest for devel
         run: python imgen.py
       - name: Save devel's manifest