Cannot add contributors when `commitConvention` is set to gitmoji,

[iqfareez]

Describe the bug Adding contributors failed when using gitmoji in the commitConvention

To Reproduce Steps to reproduce the behavior:

1. Install all-contributors bot
2. Create new repo (or can use existing)
3. Add first contributors. Eg @all-contributors please add @fareez2 for code & test
4. Merge the first PR created by the bot (including README and .all-contributorsrc files)
5. In .all-contributorsrc, change commitConvention to gitmoji. Commit the changes
6. Add another contributor. Eg: @all-contributors please add @iqfareez for docs & test

Expected behavior A new PR should be created with contributor iqfareez.

Actual behavior

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Additional context

Changed back to other entries other than gitmoji fixes the issue.