spack.yaml: Now requires variants rather than prefers

spack.yaml

@@ -7,27 +7,35 @@ spack:
     - [email protected]
   packages:
     access-om3-nuopc:
-      require: '@git.0.3.0'
-      variants: +install_libraries
+      require:
+        - '@git.0.3.0'
+        - +install_libraries
 
     esmf:
-      require: '@8.5.0'
-      variants: +debug
+      require:
+        - '@8.5.0'
+        - +debug
     parallelio:
-      require: '@2.6.2'
-      variants: build_type=RelWithDebInfo fflags='-qno-opt-dynamic-align -convert big_endian -assume byterecl -ftz -traceback -assume realloc_lhs -fp-model source' cflags='-qno-opt-dynamic-align -fp-model precise -std=gnu99'
+      require:
+        - '@2.6.2'
+        - build_type=RelWithDebInfo fflags='-qno-opt-dynamic-align -convert big_endian -assume byterecl -ftz -traceback -assume realloc_lhs -fp-model source' cflags='-qno-opt-dynamic-align -fp-model precise -std=gnu99'
     netcdf-c:
-      require: '@4.9.2'
-      variants: build_system=cmake build_type=RelWithDebInfo
+      require:
+        - '@4.9.2'
+        - build_system=cmake build_type=RelWithDebInfo
     netcdf-fortran:
-      require: '@4.6.1'
+      require:
+        - '@4.6.1'
     fms:
-      require: '@2023.02'
-      variants: precision=64 +large_file +deprecated_io ~gfs_phys ~openmp ~quad_precision build_type=RelWithDebInfo
+      require:
+        - '@2023.02'
+        - precision=64 +large_file +deprecated_io ~gfs_phys ~openmp ~quad_precision build_type=RelWithDebInfo
     openmpi:
-      require: '@4.1.5'
+      require:
+        - '@4.1.5'
     fortranxml:
-      require: '@4.1.2'
+      require:
+        - '@4.1.2'
 
     all:
       compiler: [[email protected]]