HOME should be added to the environment

[dpryan79]

On OSX CI nodes, $HOME isn't set in new shells, which always causes headaches for things like rust (e.g., https://github.com/bioconda/bioconda-recipes/pull/34374 ). We can set $HOME before running bioconda-utils, but that variable doesn't exist in the build scripts for packages. We need to ensure that it gets injected into the environment in which those scripts are run.