python313Packages.dsmr-parser: fix dependency relaxation

The dependency name needs to match the representation in the wheel
metadata.

pkgs/development/python-modules/dsmr-parser/default.nix

···
     hash = "sha256-NfleByW9MF7FS4n/cMv297382LucP6Z629CuA6chm20=";
   };
 
-  pythonRelaxDeps = [ "dlms-cosem" ];
+  pythonRelaxDeps = [ "dlms_cosem" ];
 
   build-system = [ setuptools ];