Revert "Try a pre_build step."

This reverts commit 0470dee.

.readthedocs.yml

@@ -17,8 +17,6 @@ build:
       - git stash
     post_install:
       - git stash pop
-    pre_build:
-      - python -c "from geovista.cache import fetch_coastlines; _ = fetch_coastlines();"
 
 conda:
   environment: requirements/readthedocs.yml