ci(vale): use json formatted file list

Request a JSON formatted file list to prevent any issues with file name
conventions. This also fixes the current issue with the multiple file
changes resulting in needlessly parsing all files in the repository.

Signed-off-by: Randolph Sapp <rs@ti.com>

Author: StaticRocket

.github/workflows/vale.yml

@@ -27,6 +27,7 @@ jobs:
         id: changed-files
         uses: tj-actions/changed-files@v46
         with:
+          json: true
           files: |
             **.rst
             **.md