Update the master CI workflow (#881)

This should fix the master build, since it seems that we are caching what we shouldn't.

.github/workflows/master.yml

@@ -30,7 +30,9 @@ jobs:
           command: doc
           args: -v --document-private-items
       - run: echo "<meta http-equiv=refresh content=0;url=boa/index.html>" > target/doc/index.html
-      - run: mkdir target/doc_upload && mv target/doc target/doc_upload/doc
+      - run: |
+          if [ -d target/doc_upload ]; then rm -rf target/doc_upload; fi
+          mkdir target/doc_upload && mv target/doc target/doc_upload/doc
       - name: Upload documentation
         uses: crazy-max/ghaction-github-pages@v2
         with: