Use selectors in the environment file to install correct resource directory, and make openmp tests pass

Author: mcbarton

environment-dev.yml

@@ -5,8 +5,9 @@ dependencies:
   # Build dependencies
   - make
   - cmake
-  - clangxx # [not win]
-  - cxx-compiler # [win]
+  - sel(unix): clangxx=21
+  - sel(win): cxx-compiler
+  - sel(linux): cxx-compiler
   # Host dependencies
   - xeus>=6.0.0
   - xeus-zmq
@@ -15,7 +16,7 @@ dependencies:
   - CppInterOp>=1.8
   - pugixml
   - cpp-argparse
-  - llvm-openmp
+  - sel(unix): llvm-openmp=21
   - curl
   - libcurl
   - libcurl-static