chore: Re-enable Python 3.12 testing

Author: pawamoy

Diff for: Makefile

@@ -1,7 +1,7 @@
 .DEFAULT_GOAL := help
 SHELL := bash
 DUTY := $(if $(VIRTUAL_ENV),,pdm run) duty
-export PDM_MULTIRUN_VERSIONS ?= 3.8 3.9 3.10 3.11
+export PDM_MULTIRUN_VERSIONS ?= 3.8 3.9 3.10 3.11 3.12
 
 args = $(foreach a,$($(subst -,_,$1)_args),$(if $(value $a),$a="$($a)"))
 check_quality_args = files

Diff for: pyproject.toml

@@ -21,6 +21,7 @@ classifiers = [
     "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
+    "Programming Language :: Python :: 3.12",
     "Topic :: Documentation",
     "Topic :: Software Development",
     "Topic :: Utilities",