[`flake8-bandit`] Fix correct example for `S308` (#21128)

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## Summary
Fixed the incorrect import example in the "correct exmaple"
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## Test Plan
🤷 
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crates/ruff_linter/src/rules/flake8_bandit/rules/suspicious_function_call.rs

@@ -375,7 +375,7 @@ impl Violation for SuspiciousEvalUsage {
 ///
 ///
 /// def render_username(username):
-///     return django.utils.html.format_html("<i>{}</i>", username)  # username is escaped.
+///     return format_html("<i>{}</i>", username)  # username is escaped.
 /// ```
 ///
 /// ## References