fix test file path from the 7fcad6e commit

[tbhaxor]

Description

In the commit 7fcad6e the file rename was done test/plugins/alias-completion.plugin.bats → test/completion/aliases.completion.bats. This PR resolve the file not found error caused while performing lint on the old file

For more context, check this build output

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• If my change requires a change to the documentation, I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• If I have added a new file, I also added it to clean_files.txt and formatted it using lint_clean_files.sh.
• I have added tests to cover my changes, and all the new and existing tests pass.

[NoahGorny]

Nice fix @tbhaxor
Weird that we didn't see it in the original pr