fix: remove deprecated --exclude-mail flag from lychee args

lychee v0.21.0 (bundled with lychee-action v2.8.0) removed the
--exclude-mail flag. Mail links are now excluded by default, so
the flag is no longer needed. This fixes the broken-links-checker
workflow failure.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Yamini-Microsoft

.github/workflows/broken-links-checker.yml

@@ -37,7 +37,7 @@ jobs:
         uses: lycheeverse/lychee-action@v2.8.0
         with:
           args: >
-            --verbose --exclude-mail --no-progress --exclude ^https?://
+            --verbose --no-progress --exclude ^https?://
             ${{ steps.changed-markdown-files.outputs.all_changed_files }}
           failIfEmpty: false
         env:
@@ -50,7 +50,7 @@ jobs:
         uses: lycheeverse/lychee-action@v2.8.0
         with:
           args: >
-            --verbose --exclude-mail --no-progress --exclude ^https?://
+            --verbose --no-progress --exclude ^https?://
             '**/*.md'
           failIfEmpty: false
         env: