Fix code repos: move repos.json to root _data/ for Eleventy 3

Eleventy 3 only loads global data from inputDir/_data/, not from
subdirectory _data/ dirs. Moved code/_data/repos.json to _data/repos.json
and updated the GitHub aggregator output path.

scripts/github-aggregator/aggregate.py

@@ -14,7 +14,7 @@ import urllib.request
 GITHUB_USER = "skoelle"
 API_ROOT = "https://api.github.com"
 OUTPUT_PATH = os.path.join(
-    os.path.dirname(__file__), "..", "..", "code", "_data", "repos.json"
+    os.path.dirname(__file__), "..", "..", "_data", "repos.json"
 )