Pin py-torch to 1.9.1

(due to a known build fail of 1.10.x → to be investigated later)

spack.yaml

@@ -42,7 +42,7 @@ spack:
     - py-hippounit@1.3.6
     - py-efel@4.0.4
     - py-hbp-neuromorphic-platform@0.10.1
-    - py-torch~cuda~rocm~valgrind~mkldnn~mpi~gloo~tensorpipe~onnx_ml ^protobuf@:3.17.999
+    - py-torch~cuda~rocm~valgrind~mkldnn~mpi~gloo~tensorpipe~onnx_ml@1.9.1 ^protobuf@:3.17.999
     - py-lfpy@2.2.6
     #- biobb-common
     # demo for codejam12