[flake8-type-checking] Stabilize runtime-cast-value (TC006) (#16637)

Summary
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Stabilizes TC006. The test was already in the right place.

Test Plan
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No open issues or PRs. The last related [issue] was closed on
2025-02-09.

[issue]: #16037

Author: ntBre

crates/ruff_linter/src/codes.rs

@@ -871,7 +871,7 @@ pub fn code_to_rule(linter: Linter, code: &str) -> Option<(RuleGroup, Rule)> {
         (Flake8TypeChecking, "003") => (RuleGroup::Stable, rules::flake8_type_checking::rules::TypingOnlyStandardLibraryImport),
         (Flake8TypeChecking, "004") => (RuleGroup::Stable, rules::flake8_type_checking::rules::RuntimeImportInTypeCheckingBlock),
         (Flake8TypeChecking, "005") => (RuleGroup::Stable, rules::flake8_type_checking::rules::EmptyTypeCheckingBlock),
-        (Flake8TypeChecking, "006") => (RuleGroup::Preview, rules::flake8_type_checking::rules::RuntimeCastValue),
+        (Flake8TypeChecking, "006") => (RuleGroup::Stable, rules::flake8_type_checking::rules::RuntimeCastValue),
         (Flake8TypeChecking, "007") => (RuleGroup::Stable, rules::flake8_type_checking::rules::UnquotedTypeAlias),
         (Flake8TypeChecking, "008") => (RuleGroup::Preview, rules::flake8_type_checking::rules::QuotedTypeAlias),
         (Flake8TypeChecking, "010") => (RuleGroup::Stable, rules::flake8_type_checking::rules::RuntimeStringUnion),