Try changing https://repo.mamba.pm/conda-forge to just conda-forge in environment-wasm-host.yml

Author: mcbarton

environment-wasm-host.yml

@@ -1,7 +1,7 @@
 name: xeus-cpp-wasm-host
 channels:
   - https://repo.prefix.dev/emscripten-forge-dev
-  - https://repo.mamba.pm/conda-forge
+  - conda-forge
 dependencies:
   - nlohmann_json
   - nlohmann_json-abi