Docs: exclude stackoverflow.com from lychee link check

Stack Overflow returns 403 to automated requests, so the CUDA-version
link in docs/documentation/docker.md fails the docs link check even
though it resolves fine in a browser. Same class of exclusion already
present for the Microsoft Store, VS Code, and OLCF Summit pages.

Author: sbryngelson

.lychee.toml

@@ -31,4 +31,5 @@ exclude = [
     "https://www\\.olcf\\.ornl\\.gov/summit",            # Returns 503 to automated requests
     "https://apps\\.microsoft\\.com/store/detail/",  # Microsoft Store detail pages return 403 to automated requests
     "https://code\\.visualstudio\\.com/?$",           # Root page returns 403 to automated requests
+    "https://stackoverflow\\.com",                    # Returns 403 to automated requests
 ]