fix: restore CallThem linter that got unlinked from the project at some point

[hippietrail]

Issues

N/A

I definitely discovered this unlinked CallThem module once before. I must've only mentioned on Discord or in another issue or PR, such as the one for checking the curated LintGroup.

Description

There's been a CallThem linter for some time but at some point it lost its link in linting/lint_group.rs, which has since become linting/lint_group/mod.rs but the call_them.rs remained as did the link in linting/mod.rs

How Has This Been Tested?

cargo test is 100% successful, even the old tests in the call_them.rs

Checklist

• I have performed a self-review of my own code
• I have added tests to cover my changes
• I have considered splitting this into smaller pull requests.