Fix target Python version in ruff configuration to 3.12

Author: jshn9515

dnnlpy/ruff.toml

@@ -32,8 +32,8 @@ exclude = [
 line-length = 88
 indent-width = 4
 
-# Assume Python 3.14
-target-version = "py314"
+# Assume Python 3.12
+target-version = "py312"
 
 [lint]
 # Enable Pyflakes (`F`) and a subset of the pycodestyle (`E`) codes by default.