Update ovos-skill-fallback-unknown requirement in /requirements

Updates the requirements on [ovos-skill-fallback-unknown](https://github.com/OpenVoiceOS/skill-ovos-fallback-unknown) to permit the latest version.
- [Release notes](https://github.com/OpenVoiceOS/skill-ovos-fallback-unknown/releases)
- [Changelog](https://github.com/OpenVoiceOS/skill-ovos-fallback-unknown/blob/dev/CHANGELOG.md)
- [Commits](OpenVoiceOS/ovos-skill-fallback-unknown@V0.0.4a1...V0.0.4a2)

---
updated-dependencies:
- dependency-name: ovos-skill-fallback-unknown
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

requirements/skills-essential.txt

@@ -1,5 +1,5 @@
 ovos-skill-volume~=0.0, >=0.0.2a3
-ovos-skill-fallback-unknown~=0.0, >=0.0.4a1
+ovos-skill-fallback-unknown~=0.0
 ovos-skill-stop>=0.3.0a4
 # neon-skill-alerts>=1.5.2a2
 ovos-skill-personal~=0.0, >=0.0.4a1