Revert "Cap copier version to avoid symlink issue"

This reverts commit c8b2891.

Author: coretl

pyproject.toml

@@ -9,7 +9,7 @@ requires-python = ">=3.10"
 
 [project.optional-dependencies]
 dev = [
-    "copier < 9.4",  # https://github.com/copier-org/copier/issues/1819
+    "copier",
     "myst-parser",
     "pre-commit",
     "pydata-sphinx-theme>=0.12",