`nimble install chroma` lags behind `HEAD` by several commits

[gcr]

This is the root cause of #41.

Running nimble install chroma gets commit b2e71179174e040884ebf6a16cbac711c84620b9, which is two years old.

$ nimble install chroma
Downloading https://github.com/treeform/chroma using git
  Verifying dependencies for [email protected]
 Installing [email protected]
  Success:  chroma installed successfully.
$ cat ~/.nimble/pkgs2/chroma-0.2.7-f873f4b97e87a82e27e0b85bf9130fe3e320a2b8/nimblemeta.json
{
  "version": 1,
  "metaData": {
    "url": "https://github.com/treeform/chroma",
    "downloadMethod": "git",
    "vcsRevision": "b2e71179174e040884ebf6a16cbac711c84620b9",
    "files": [
      "/chroma/distance.nim",
      "/chroma/csstint.nim",
      "/chroma/transformations.nim",
      "/chroma/colortypes.nim",
      "/chroma.nim",
      "/chroma/blends.nim",
      "/chroma/temperature.nim",
      "/chroma.nimble",
      "/chroma/names.nim"
    ],
    "binaries": [],
    "specialVersions": [
      "0.2.7"
    ]
  }
}