Revert "Update flit-core requirement from >=3.2 to >=3.12.0"

This reverts commit fdd2707.

Author: codingjoe

pyproject.toml

@@ -1,5 +1,5 @@
 [build-system]
-requires = ["flit_core>=3.12.0", "flit_scm", "wheel"]
+requires = ["flit_core>=3.2", "flit_scm", "wheel"]
 build-backend = "flit_scm:buildapi"
 
 [project]