Revert "Merge pull request #1877 from opensafely/dependabot/github_actions/lycheeverse/lychee-action-2.7.0"

This reverts commit 10ab8a6, reversing
changes made to 50b86bc.

The link checker initially worked, but started failing after some changes to
the ehrQL docs were merged. We think this might be due to the known issue in
v2.6.1 causing the exclude-path not to work.

Author: lucyb

.github/workflows/check_links.yml

@@ -39,7 +39,7 @@ jobs:
       # https://github.com/lycheeverse/lychee/issues/36
       - name: Check links
         # 2.6.1 seemed to cause the exclude-path to not take effect, waiting for next release.
-        uses: lycheeverse/lychee-action@a8c4c7cb88f0c7386610c35eb25108e448569cb0  # v2.7.0
+        uses: lycheeverse/lychee-action@82202e5e9c2f4ef1a55a3d02563e1cb6041e5332  # v2.4.1
         with:
           args: "--exclude-all-private --include-verbatim --max-concurrency 24 --require-https --verbose --no-progress --offline
           --accept '100..=103,200..=299,429,500..=511'