fix: update lychee link checker configuration to fix CI failures

The --accept flag in lychee v2 replaces default accepted status codes
instead of adding to them, causing 200 responses to be rejected when
--accept 429 is used. Remove --accept 429 and match the working
configuration used in the caldav project (timeout 20, max-retries 3).

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: tobixen

.github/workflows/linkcheck.yml

@@ -12,8 +12,7 @@ jobs:
       with:
         fail: true
         args: >-
-          --timeout 10
-          --max-retries 2
-          --accept 429
+          --timeout 20
+          --max-retries 3
           '**/*.md'
           '**/*.rst'