BleedingEdge cats using _BETA syntax not recognized

References:

- https://github.com/akeeba/release-system/commit/afe3be028f40eae9ecd67b8688eef9d6ea9e18e6
- https://www.akeebabackup.com/support/akeeba-release-system/20032-path-is-not-a-folder-error-with-bleedingedge-categories.html#p111556
Merge pull request #51 from mbabker/patch-1

BleedingEdge cats using _BETA syntax not recognized