Add data/unstable-environment-arm64.yml

data/unstable-environment-arm64.yml

+name: lbenv-unstable
+channels:
+  - conda-forge
+dependencies:
+  - python =3.8
+  - pip
+  # General tools
+  - black
+  - git
+  - cmake
+  - ninja
+  - cookiecutter
+  - nose
+  - pytest
+  - flake8
+  - sphinx
+  - sphinx_rtd_theme
+  - yapf
+  # LHCb specific
+  - LbEnv
+  - LbPlatformUtils
+  - lbinstall
+  - LbDevTools
+  - LbAdmin
+  - LbCommon
+  - LbNightlyTools
+  - lbmessaging
+  - LbDiracWrappers
+  - LbScriptsLegacy
+  - LbSoftConfDb2Clients
+  - LbCondaWrappers