docs: add light/dark logos (#6627)

### Description

Display the Sentry logo in the documentation for decoration.

#### Issues
resolves: #6604

#### Reminders
- Please add tests to validate your changes, and lint your code using
`uv run ruff`.
- Add GH Issue ID _&_ Linear ID (if applicable)
- PR title should use [conventional
commit](https://develop.sentry.dev/engineering-practices/commit-messages/#type)
style (`feat:`, `fix:`, `ref:`, `meta:`)
- For external contributors:
[CONTRIBUTING.md](https://github.com/getsentry/sentry-python/blob/master/CONTRIBUTING.md),
[Sentry SDK development docs](https://develop.sentry.dev/sdk/), [Discord
community](https://discord.gg/Ww9hbqr)

Author: hwhsu1231

docs/_static/.gitkeep

@@ -95,6 +95,8 @@
 # documentation.
 #
 html_theme_options = {
+    "light_logo": "_static/logo-light.svg",
+    "dark_logo": "_static/logo-dark.svg",
     "github_url": "https://github.com/getsentry/sentry-python",
 }