[pyupgrade] Stabilize non-pep695-generic-class (UP046) (#18519)

## Summary
- Stabilizes UP046 (non-pep695-generic-class) rule by changing it from
Preview to Stable

## Test plan
- ✅ Rule is already tested in main test function, no migration needed
- ✅ `make check` passes
- ✅ `make test` passes

## Rule Documentation
- [Test
file](https://github.com/astral-sh/ruff/blob/main/crates/ruff_linter/src/rules/pyupgrade/mod.rs#L109-L110)
- [Rule
documentation](https://docs.astral.sh/ruff/rules/non-pep695-generic-class/)

crates/ruff_linter/src/codes.rs

@@ -550,7 +550,7 @@ pub fn code_to_rule(linter: Linter, code: &str) -> Option<(RuleGroup, Rule)> {
         (Pyupgrade, "043") => (RuleGroup::Stable, rules::pyupgrade::rules::UnnecessaryDefaultTypeArgs),
         (Pyupgrade, "044") => (RuleGroup::Stable, rules::pyupgrade::rules::NonPEP646Unpack),
         (Pyupgrade, "045") => (RuleGroup::Stable, rules::pyupgrade::rules::NonPEP604AnnotationOptional),
-        (Pyupgrade, "046") => (RuleGroup::Preview, rules::pyupgrade::rules::NonPEP695GenericClass),
+        (Pyupgrade, "046") => (RuleGroup::Stable, rules::pyupgrade::rules::NonPEP695GenericClass),
         (Pyupgrade, "047") => (RuleGroup::Preview, rules::pyupgrade::rules::NonPEP695GenericFunction),
         (Pyupgrade, "049") => (RuleGroup::Stable, rules::pyupgrade::rules::PrivateTypeParameter),
         (Pyupgrade, "050") => (RuleGroup::Preview, rules::pyupgrade::rules::UselessClassMetaclassType),

crates/ruff_linter/src/rules/pyupgrade/rules/pep695/non_pep695_generic_class.rs

@@ -32,7 +32,7 @@ use super::{
 /// fix.
 ///
 /// Not all type checkers fully support PEP 695 yet, so even valid fixes suggested by this rule may
-/// cause type checking to fail.
+/// cause type checking to [fail].
 ///
 /// ## Fix safety
 ///
@@ -84,6 +84,7 @@ use super::{
 /// [PYI059]: https://docs.astral.sh/ruff/rules/generic-not-last-base-class/
 /// [UP047]: https://docs.astral.sh/ruff/rules/non-pep695-generic-function/
 /// [UP049]: https://docs.astral.sh/ruff/rules/private-type-parameter/
+/// [fail]: https://github.com/python/mypy/issues/18507
 #[derive(ViolationMetadata)]
 pub(crate) struct NonPEP695GenericClass {
     name: String,