Merge branch 'unpin_py-pybind11' into 'master'

Unpin py-pybind11

See merge request technical-coordination/project-internal/devops/platform/ebrains-spack-builds!55

packages/meta-brainscales/package.py

@@ -49,7 +49,7 @@ class MetaBrainscales(Package):
     depends_on('py-matplotlib')
     depends_on('py-nose')
     depends_on('py-numpy')
-    depends_on('py-pybind11@2.6.0:2.6.999') # workaround concretization error (py-scipy doesn't like 2.7)
+    depends_on('py-pybind11')
     depends_on('py-pybind11-stubgen')
     depends_on('py-pycodestyle')
     depends_on('py-pyelftools')