Pinning nlohmann_json version for xeus-cpp-lite (#559)

Author: anutosh491

environment-wasm.yml

@@ -3,9 +3,9 @@ channels:
   - https://repo.prefix.dev/emscripten-forge-dev
 dependencies:
   - emscripten-abi==3.1.73
-  - nlohmann_json
+  - nlohmann_json=3.11.3
   - xeus-lite
   - xeus
   - cpp-argparse
   - pugixml
-  - doctest
+  - doctest