updated config to new format

containers/builder/spack.yaml

 spack:
   specs:
-    - cmake@3.18.1
-    - fmt@6.1.2 cxxstd=17
-    - spdlog@1.5.0
-    - nlohmann-json
-    - heppdt@3.04.01
-    - clhep@2.4.1.3 cxxstd=17
-    - cairo+fc+ft+X+pdf+gobject
-    - eigen@3.3.7
-    - python@3.7.8
-    - py-pip
-    - py-numpy
-    - py-pyyaml
-    - xrootd@4.12.3 cxxstd=17 +python
-    - root@6.22.00 cxxstd=17 +fftw +fortran +gdml +http +mlp +pythia8 +root7 +tmva +vc +xrootd +ssl ^mesa+opengl -llvm -osmesa
-    - pythia8@8244
-    - hepmc3@3.2.2 +python +rootio 
-    - stow@2.2.2
-    - podio@master
-    - geant4@10.6.2 cxxstd=17 +opengl +vecgeom +x11 +qt ^qt +opengl
-    - dd4hep@1.14.1 +geant4 +assimp +hepmc3
-    - acts@1.02.0 +dd4hep +digitization +identification +json +tgeo
-    - gaudi@34.0
-    - dawn@3_91a
-    - dawncut@1_54a
+  - cmake@3.18.1
+  - fmt@6.1.2 cxxstd=17
+  - spdlog@1.5.0
+  - nlohmann-json
+  - heppdt@3.04.01
+  - clhep@2.4.1.3 cxxstd=17
+  - cairo+fc+ft+X+pdf+gobject
+  - eigen@3.3.7
+  - python@3.7.8
+  - py-pip
+  - py-numpy
+  - py-pyyaml
+  - xrootd@4.12.3 cxxstd=17 +python
+  - root@6.22.00 cxxstd=17 +fftw +fortran +gdml +http +mlp +pythia8 +root7 +tmva +vc
+    +xrootd +ssl ^mesa+opengl -llvm -osmesa
+  - pythia8@8244
+  - hepmc3@3.2.2 +python +rootio
+  - stow@2.2.2
+  - podio@master
+  - geant4@10.6.2 cxxstd=17 +opengl +vecgeom +x11 +qt ^qt +opengl
+  - dd4hep@1.14.1 +geant4 +assimp +hepmc3
+  - acts@1.02.0 +dd4hep +digitization +identification +json +tgeo
+  - gaudi@34.0
+  - dawn@3_91a
+  - dawncut@1_54a
   concretization: together
-  config:
-    install_tree: /opt/software
+  config: 
+    install-tree: 
+      root: /opt/software
   view: /usr/local