False positive lint `version_constraints_missing_whitespacewhen` for unequal constraint `!=`

[corneliusroemer]

bioconda-utils lint wrongly throws an error for a version constraint with !=:

requirements:
  run:
    - fsspec !=2023.9.1

ERROR: recipes/nextstrain-cli/meta.yaml:45: version_constraints_missing_whitespace: Packages and their version constraints must be space sepa

This was noticed in bioconda/bioconda-recipes#43160

[corneliusroemer]

You can find a failing test in #919