py-pdm_backend: updated to 2.1.2

2.1.2
Fix file permissions to 644 for wheel

2.1.1
Pdm-backend should not normalize names in project metadata

2.1.0
�泅� Features

Change the default build dir to a pdm-specific one
Allow to include files in wheel .data directory

�汾� Bug Fixes

Scm versionning fails when package is not top-level directory
Cleanup logic to first check config_settings
Raise an error when SCM version can't be determined

�沒� Documentation

Clarify order of pdm_build_initialize and pdm_build_clean

(adam)