Fixed: Update gradle wrapper validation in CI

Replace `gradle/wrapper-validation-action@v3` with
`gradle/actions/wrapper-validation@5` which should fix the error seen
e.g. [here](https://github.com/termux/termux-app/actions/runs/20685857619/job/59386383274):

> Error: The action gradle/actions/wrapper-validation@v3.5.0 is not allowed in termux/termux-app because all actions must be from a repository owned by termux, created by GitHub, or match one of the patterns: gradle/actions/dependency-submission@*, gradle/wrapper-validation-action@v*.