Clean out .tmp before running tests

.github/workflows/test.yml

@@ -13,7 +13,7 @@ jobs:
           submodules: "recursive"
       - name: Build arweave test sources
         run: |
-          rm -rf _build || true
+          rm -rf _build .tmp || true
           ./ar-rebar3 test compile
           chmod -R u+w ./_build
           tar --dereference -czf /tmp/arweave_build_${{ github.run_id }}.tar.gz _build