Added new version of Frites

I'm working on a Jupyter notebook that requires to import a function (conn_fit) which is only available in the latest version of Frites (0.4.4). So I added this version in the py-frites/package.py.

spack.yaml

@@ -24,7 +24,7 @@ spack:
     - py-efel@4.0.4
     - py-elephant@0.13.0
     - py-fairgraph@0.11.0
-    - py-frites@0.4.3
+    - py-frites@0.4.4
     - py-hbp-archive@1.1.1
     - py-hbp-neuromorphic-platform@0.10.1
     - py-hbp-validation-client@0.8.2