fix the python_version getting

Author: aignas

python/uv/private/lock.bzl

@@ -75,9 +75,13 @@ def _args(ctx):
 
 def _lock_impl(ctx):
     srcs = ctx.files.srcs
+    python_version = full_version(
+        version = ctx.attr.python_version or DEFAULT_PYTHON_VERSION,
+        minor_mapping = MINOR_MAPPING,
+    )
     output = ctx.actions.declare_file("{}.{}.out".format(
         ctx.label.name,
-        ctx.attr.python_version.replace(".", "_"),
+        python_version.replace(".", "_"),
     ))
 
     toolchain_info = ctx.toolchains[UV_TOOLCHAIN_TYPE]
@@ -216,10 +220,6 @@ modifications and the locking is not done from scratch.
         ),
         "python_version": attr.string(
             doc = "Public, see the docs in the macro.",
-            default = full_version(
-                version = DEFAULT_PYTHON_VERSION,
-                minor_mapping = MINOR_MAPPING,
-            ) if BZLMOD_ENABLED else "",
         ),
         "srcs": attr.label_list(
             mandatory = True,
@@ -412,7 +412,8 @@ def lock(
             are compiling the requirements file for using it as a constraints
             file. Defaults to `False`.
         python_version: {type}`str | None` the python_version to transition to
-            when locking the requirements.
+            when locking the requirements. Defaults to the default python version
+            configured by the {obj}`python` module extension.
         target_compatible_with: The `target_compatible_with` for the locking action.
         tags: The common tags for all of the targets. This defaults to [`manual`].
             Note, that the locking target also adds `requires-network` and