Respect dummy-variable-rgx for unused bound exceptions (#6492)

## Summary

This PR respects our unused variable regex when flagging bound
exceptions, so that you no longer get a violation for, e.g.:

```python
def f():
    try:
        pass
    except Exception as _:
        pass
```

This is an odd pattern, but I think it's surprising that the regex
_isn't_ respected here.

Closes #6391

## Test Plan

`cargo test`

crates/ruff/resources/test/fixtures/pyflakes/F841_0.py

@@ -145,3 +145,9 @@ def do_thing(self):
  obj = Foo()
  obj.do_thing()
 
+
+def f():
+ try:
+ pass
+ except Exception as _:
+ pass

crates/ruff/src/checkers/ast/analyze/bindings.rs

@@ -18,7 +18,13 @@ pub(crate) fn bindings(checker: &mut Checker) {
 
  for binding in checker.semantic.bindings.iter() {
  if checker.enabled(Rule::UnusedVariable) {
- if binding.kind.is_bound_exception() && !binding.is_used() {
+ if binding.kind.is_bound_exception()
+ && !binding.is_used()
+ && !checker
+ .settings
+ .dummy_variable_rgx
+ .is_match(binding.name(checker.locator))
+ {
  let mut diagnostic = Diagnostic::new(
  pyflakes::rules::UnusedVariable {
  name: binding.name(checker.locator).to_string(),

crates/ruff/src/rules/pyflakes/rules/unused_variable.rs

@@ -312,10 +312,13 @@ pub(crate) fn unused_variable(checker: &Checker, scope: &Scope, diagnostics: &mu
  && !binding.is_global()
  && !binding.is_used()
  && !checker.settings.dummy_variable_rgx.is_match(name)
- && name != "__tracebackhide__"
- && name != "__traceback_info__"
- && name != "__traceback_supplement__"
- && name != "__debuggerskip__"
+ && !matches!(
+ name,
+ "__tracebackhide__"
+ | "__traceback_info__"
+ | "__traceback_supplement__"
+ | "__debuggerskip__"
+ )
  {
  return Some((name.to_string(), binding.range, binding.source));
  }

crates/ruff/src/rules/pyflakes/snapshots/ruff__rules__pyflakes__tests__f841_dummy_variable_rgx.snap

@@ -256,4 +256,22 @@ F841_0.py:127:21: F841 Local variable `value` is assigned to but never used
  |
  = help: Remove assignment to unused variable `value`
 
+F841_0.py:152:25: F841 [*] Local variable `_` is assigned to but never used
+ |
+150 | try:
+151 | pass
+152 | except Exception as _:
+ | ^ F841
+153 | pass
+ |
+ = help: Remove assignment to unused variable `_`
+
+ℹ Fix
+149 149 | def f():
+150 150 | try:
+151 151 | pass
+152 |- except Exception as _:
+ 152 |+ except Exception:
+153 153 | pass
+