tools: update prohibited-strings md linting

Update to remark-lint-prohibited-strings 1.0.3 to avoid false positives
with GitHub team names which must be lowercased no matter what our
prohibited-strings rules say about a particular string.

PR-URL: #20742
Refs: #20740
Reviewed-By: Ruben Bridgewater <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Michael Dawson <[email protected]>
Reviewed-By: Trivikram Kamat <[email protected]>
Reviewed-By: James M Snell <[email protected]>