Bleach 6 update (#4610)

* Update bleach requirement from ==5.0.* to ==6.2.*

Updates the requirements on [bleach](https://github.com/mozilla/bleach) to permit the latest version.
- [Changelog](https://github.com/mozilla/bleach/blob/main/CHANGES)
- [Commits](https://github.com/mozilla/bleach/compare/v5.0.0...v6.2.0)

---
updated-dependencies:
- dependency-name: bleach
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

* Update bleach parameter types

* Fix tests

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

src/tests/base/test_rich_text.py

@@ -137,7 +137,7 @@ def test_markdown_email_custom_allowlist():
     source = "![my image](https://example.org/my-image.jpg)"
     html = markdown_compile_email(
         source,
-        allowed_tags=ALLOWED_TAGS + ["img"],
+        allowed_tags=ALLOWED_TAGS | {"img"},
         allowed_attributes=dict(ALLOWED_ATTRIBUTES, img=["src", "alt", "title"]),
     )
     assert html == '<p><img alt="my image" src="https://example.org/my-image.jpg"></p>'