fix(grab_forged_keys): don't pass geo & time as other_keys

[brookslogan]

Checklist

Please:

• Make sure this PR is against "dev", not "main".
• Request a review from one of the current epipredict main reviewers:
  dajmcdon.
• Make sure to bump the version number in DESCRIPTION and NEWS.md.
  Always increment the patch version number (the third number), unless you are
  making a release PR from dev to main, in which case increment the minor
  version number (the second number).
• [-] Describe changes made in NEWS.md, making sure breaking changes
  (backwards-incompatible changes to the documented interface) are noted.
  Collect the changes under the next release number (e.g. if you are on
  0.7.2, then write your changes under the 0.8 heading).
  • This is a fix for an improvement under the 0.2 heading; it didn't make sense to write "fixed thing that didn't exist yet".
• Consider pinning the epiprocess version in the DESCRIPTION file if
  • You anticipate breaking changes in epiprocess soon
  • You want to co-develop features in epipredict and epiprocess

Change explanations for reviewer

"geo_value" and "time_value" were being passed as other_keys when trying to make grabbed forged keys into epi_dfs. This fixes that.

Magic GitHub syntax to mark associated Issue(s) as resolved when this is merged into the default branch

• Resolves #{issue number}