Corrected name of pynn package

spack.yaml

@@ -6,6 +6,6 @@ spack:
     - nest@2.20.0 +python +gsl +mpi %gcc@10.3.0
     - arbor +mpi %gcc@10.3.0
     - neuron +mpi %gcc@10.3.0
-    - PyNN
+    - py-pynn %gcc@10.3.0 
     # BrainScaleS (plus some constraining)
     #- visionary-dls-core ^py-setuptools-scm+toml ^python@3.8.0:3.8.999 ^binutils+ld ^py-astroid@2.5.6:2.6.999 ^py-scipy@:1.6.999 %gcc@10.3.0