Assume everything unchanged for future-proofing

c.f. [this suggestion](#539 (comment))

.readthedocs.yml

@@ -9,7 +9,7 @@ build:
     python: "mambaforge-22.9"
   jobs:
     pre_install:
-      - git update-index --assume-unchanged environment-dev.yml mkdocs.yml
+      - git update-index --assume-unchanged .
     post_checkout:
       # Check out the full depth for setuptools-scm
       - git fetch --unshallow || true