⏪️ Revert "🔥 Remove exec line from git hook"

This reverts commit d13b964.

Turns out this line was needed after all. Without it, you end up with
some garbage in the search bar of the CLI when using `git commit -a`.

src/main.rs

@@ -217,5 +217,6 @@ const HOOK_PATH: &str = ".git/hooks/prepare-commit-msg";
 const HOOK_CONTENT: &str = r#"
 #!/usr/bin/env bash
 # gimoji as a commit hook
+exec < /dev/tty
 gimoji --hook $1 $2
 "#;