aider: Excluded the _posts/OLD directory to resolve file conflicts during Jekyll build.

# Aider chat conversation:

USER: didn't work: bash-5.1# jekyll build
ruby 3.1.1p18 (2022-02-18 revision 53f5fc4236) [x86_64-linux-musl]
Configuration file: /srv/jekyll/_config.yml
            Source: /srv/jekyll
       Destination: /srv/jekyll/_site
 Incremental build: disabled. Enable with --incremental
      Generating...
          Conflict: The following destination is shared by multiple files.
                    The written file may end up with unexpected contents.
                    /srv/jekyll/_site/2024/05/13/models-over-time.html
                     - /srv/jekyll/_posts/2024-05-13-models-over-time.md
                     - /srv/jekyll/_posts/OLD/2024-05-13-models-over-time.md

          Conflict: The following destination is shared by multiple files.
                    The written file may end up with unexpected contents.
                    /srv/jekyll/_site/2024/05/22/swe-bench-lite.html
                     - /srv/jekyll/_posts/2024-05-22-swe-bench-lite.md
                     - /srv/jekyll/_posts/OLD/2024-05-22-swe-bench-lite.md

ASSISTANT: The issue is that Jekyll is detecting multiple files that would generate the same output file, causing a conflict. This is happening because the `"**/OLD"` exclude pattern is not working as expected.

To fix this, we need to change the exclude pattern to explicitly exclude the `_posts/OLD` directory.

Here is the *SEARCH/REPLACE* block to make that change:

_config.yml
```yaml
<<<<<<< SEARCH
exclude:
  - tmp.benchmarks
  - "**/OLD"
=======
exclude:
  - tmp.benchmarks
  - _posts/OLD
>>>>>>> REPLACE
```

This will tell Jekyll to specifically exclude the `_posts/OLD` directory and avoid the file conflicts.

_config.yml

@@ -14,4 +14,4 @@ defaults:
 
 exclude:
   - tmp.benchmarks
-  - "**/OLD"
+  - _posts/OLD