Bump x509-limbo and/or wycheproof in CI (#15482)

Co-authored-by: pyca-boringbot[bot] <pyca-boringbot[bot]+106132319@users.noreply.github.com>

Author: pyca-boringbot[bot]

.github/actions/fetch-vectors/action.yml

@@ -28,7 +28,7 @@ runs:
         wait "$wycheproof_pid"
         wait "$x509_limbo_pid"
       env:
-        # Latest commit on the wycheproof main branch, as of Aug 18, 2026.
-        WYCHEPROOF_REF: "4bb5ed764261bb3699f93567998a3467d3cc9785" # wycheproof-ref
+        # Latest commit on the wycheproof main branch, as of Aug 19, 2026.
+        WYCHEPROOF_REF: "dac1dd4729fd1f8dd9e1e9f3dce51d783da6c166" # wycheproof-ref
         # Latest commit on the x509-limbo main branch, as of Aug 18, 2026.
         X509_LIMBO_REF: "c6040f178a947b3fa4d4a5c118d5594f0e0ca6e2" # x509-limbo-ref