Add standard-aifc and standard-sunau as dependencies for python 3.13 …

…and above.

Python core removed these modules in 3.13 as part of PEP-594 https://peps.python.org/pep-0594/
The standard-* modules are forks of the modules that had previously been in the python core.
Fixes beetbox#144

pyproject.toml

@@ -22,6 +22,10 @@ classifiers = [
     'License :: OSI Approved :: MIT License',
 ]
 license = {file = "LICENSE"}
+dependencies = [
+    "standard-aifc; python_version >= '3.13'",
+    "standard-sunau; python_version >= '3.13'",
+]
 
 [project.optional-dependencies]
 test = [