build(deps): bump third_party/litex from `95b310e` to `67e8d77`

Bumps [third_party/litex](https://github.com/enjoy-digital/litex) from `95b310e` to `67e8d77`.
- [Release notes](https://github.com/enjoy-digital/litex/releases)
- [Commits](https://github.com/enjoy-digital/litex/compare/95b310ee0f0d9e78e00eb32b71324b25265da4f4...67e8d774211f5c8bc682168abd27f8c9b7bb7ca2)

---
updated-dependencies:
- dependency-name: third_party/litex
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
diff --git a/third_party/litex b/third_party/litex
index 95b310e..67e8d77 160000
--- a/third_party/litex
+++ b/third_party/litex
@@ -1 +1 @@
-Subproject commit 95b310ee0f0d9e78e00eb32b71324b25265da4f4
+Subproject commit 67e8d774211f5c8bc682168abd27f8c9b7bb7ca2