ci: drop directories from windows release

Puts windows release in line with others which have the executable on the top level

.github/workflows/ci.yaml

@@ -222,7 +222,7 @@ jobs:
           tar cJvf "release-bundle/postgrest-${GITHUB_REF_NAME}-ubuntu-aarch64.tar.xz" \
             -C artifacts/postgrest-ubuntu-aarch64 postgrest
 
-          zip "release-bundle/postgrest-${GITHUB_REF_NAME}-windows-x64.zip" \
+          zip --junk-paths "release-bundle/postgrest-${GITHUB_REF_NAME}-windows-x64.zip" \
             artifacts/postgrest-windows-x64/postgrest.exe
 
       - name: Save release bundle