[flake8-return] Consider exception suppress for unnecessary assignment (#9673)

## Summary

This review contains a fix for
[RET504](https://docs.astral.sh/ruff/rules/unnecessary-assign/)
(unnecessary-assign)

The problem is that Ruff suggests combining a return statement inside
contextlib.suppress. Even though it is an unsafe fix it might lead to an
invalid code that is not equivalent to the original one.

See: https://github.com/astral-sh/ruff/issues/5909

## Test Plan

```bash
cargo test
```

crates/ruff_linter/resources/test/fixtures/flake8_return/RET504.py

@@ -363,3 +363,46 @@ def foo():
 def mavko_debari(P_kbar):
     D=0.4853881 + 3.6006116*P - 0.0117368*(P-1.3822)**2
     return D
+
+
+# contextlib suppress in with statement
+import contextlib
+
+
+def foo():
+    x = 2
+    with contextlib.suppress(Exception):
+        x = x + 1
+    return x
+
+
+def foo(data):
+    with open("in.txt") as file_out, contextlib.suppress(IOError):
+        file_out.write(data)
+        data = 10
+    return data
+
+
+def foo(data):
+    with open("in.txt") as file_out:
+        file_out.write(data)
+        with contextlib.suppress(IOError):
+            data = 10
+    return data
+
+
+def foo():
+    y = 1
+    x = 2
+    with contextlib.suppress(Exception):
+        x = 1
+    y = y + 2
+    return y  # RET504
+
+
+def foo():
+    y = 1
+    if y > 0:
+        with contextlib.suppress(Exception):
+            y = 2
+        return y