Stabilize os-symlink (PTH211) (#20229)

Summary
--

Rule and test/snapshot updated, the docs look good

My one hesitation here is that we could hold off stabilizing the rule
until its fix is also ready for stabilization, but this is also the only
preview PTH rule, so I think it's okay to stabilize the rule and later
(probably in the next minor release) stabilize the fixes together.

Author: ntBre

crates/ruff_linter/src/codes.rs

@@ -956,7 +956,7 @@ pub fn code_to_rule(linter: Linter, code: &str) -> Option<(RuleGroup, Rule)> {
         (Flake8UsePathlib, "207") => (RuleGroup::Stable, rules::flake8_use_pathlib::rules::Glob),
         (Flake8UsePathlib, "208") => (RuleGroup::Stable, rules::flake8_use_pathlib::violations::OsListdir),
         (Flake8UsePathlib, "210") => (RuleGroup::Stable, rules::flake8_use_pathlib::rules::InvalidPathlibWithSuffix),
-        (Flake8UsePathlib, "211") => (RuleGroup::Preview, rules::flake8_use_pathlib::rules::OsSymlink),
+        (Flake8UsePathlib, "211") => (RuleGroup::Stable, rules::flake8_use_pathlib::rules::OsSymlink),
 
         // flake8-logging-format
         (Flake8LoggingFormat, "001") => (RuleGroup::Stable, rules::flake8_logging_format::violations::LoggingStringFormat),

crates/ruff_linter/src/rules/flake8_use_pathlib/mod.rs

@@ -129,7 +129,6 @@ mod tests {
     #[test_case(Rule::OsPathGetatime, Path::new("PTH203.py"))]
     #[test_case(Rule::OsPathGetmtime, Path::new("PTH204.py"))]
     #[test_case(Rule::OsPathGetctime, Path::new("PTH205.py"))]
-    #[test_case(Rule::OsSymlink, Path::new("PTH211.py"))]
     fn preview_flake8_use_pathlib(rule_code: Rule, path: &Path) -> Result<()> {
         let snapshot = format!(
             "preview__{}_{}",