ci: Test pathogen-repo-ci against ebola rather than zika for now

Fixes failures due to the recent reorganization of the zika repo to
match our proposed common layout going forward, which pathogen-repo-ci
doesn't yet support.¹

¹ <#62>

.github/workflows/ci.yaml

@@ -18,7 +18,11 @@ jobs:
   test-pathogen-repo-ci:
     uses: ./.github/workflows/pathogen-repo-ci.yaml
     with:
-      repo: nextstrain/zika
+      # XXX TODO: Revert back to nextstrain/zika (for consistency with
+      # elsewhere) once pathogen-repo-ci has support for running workflows in
+      # subdirs (i.e. for our new repo layout).
+      #   -trs, 30 Jan 2024
+      repo: nextstrain/ebola
     secrets: inherit
 
   test-pathogen-repo-ci-no-example-data: