Update CHANGELOG.md with the new commits for 0.8.1 (#14664)

The 0.8.1 release was delayed, so this PR updates the CHANGELOG.md with
the latest commits on `main`.

CHANGELOG.md

@@ -21,6 +21,7 @@
 - \[`ruff`\] Auto-add `r` prefix when string has no backslashes for `unraw-re-pattern` (`RUF039`) ([#14536](https://github.com/astral-sh/ruff/pull/14536))
 - \[`ruff`\] Implement `invalid-assert-message-literal-argument` (`RUF040`) ([#14488](https://github.com/astral-sh/ruff/pull/14488))
 - \[`ruff`\] Implement `unnecessary-nested-literal` (`RUF041`) ([#14323](https://github.com/astral-sh/ruff/pull/14323))
+- \[`ruff`\] Implement `unnecessary-regular-expression` (`RUF055`) ([#14659](https://github.com/astral-sh/ruff/pull/14659))
 
 ### Rule changes
 
@@ -34,6 +35,8 @@
 
 - Avoid fixing code to `None | None` for `redundant-none-literal` (`PYI061`) and `never-union` (`RUF020`) ([#14583](https://github.com/astral-sh/ruff/pull/14583), [#14589](https://github.com/astral-sh/ruff/pull/14589))
 - \[`flake8-bugbear`\] Fix `mutable-contextvar-default` to resolve annotated function calls properly (`B039`) ([#14532](https://github.com/astral-sh/ruff/pull/14532))
+- \[`flake8-pyi`, `ruff`\] Fix traversal of nested literals and unions (`PYI016`, `PYI051`, `PYI055`, `PYI062`, `RUF041`) ([#14641](https://github.com/astral-sh/ruff/pull/14641))
+- \[`flake8-pyi`\] Avoid rewriting invalid type expressions in `unnecessary-type-union` (`PYI055`) ([#14660](https://github.com/astral-sh/ruff/pull/14660))
 - \[`flake8-type-checking`\] Avoid syntax errors and type checking problem for quoted annotations autofix (`TC003`, `TC006`) ([#14634](https://github.com/astral-sh/ruff/pull/14634))
 - \[`pylint`\] Do not wrap function calls in parentheses in the fix for unnecessary-dunder-call (`PLC2801`) ([#14601](https://github.com/astral-sh/ruff/pull/14601))
 - \[`ruff`\] Handle `attrs`'s `auto_attribs` correctly (`RUF009`) ([#14520](https://github.com/astral-sh/ruff/pull/14520))