Sherlock: Command Injection via pull_request_target in validate_modified_targets.yml

Sherlock hunts down social media accounts by username across social networks. Prior to 0.16.1, the GitHub Actions workflow validate_modified_targets.yml is vulnerable to command injection via the pull_request_target trigger. Any GitHub user can execute arbitrary commands on the CI runner and exfiltrate the GITHUB_TOKEN by opening a pull request. No approval, review, or merge is required. This vulnerability is fixed in 0.16.1.