Add support for Python 3.13 (#280)

Add support for Python 3.13, and release 3.13.0.

The default Python version remains unchanged (at 3.12) for now.

Release announcement:
https://blog.python.org/2024/10/python-3130-final-released.html
https://www.python.org/downloads/release/python-3130/

Details on what's new in Python 3.13:
https://docs.python.org/3.13/whatsnew/3.13.html

Binary builds:
https://github.com/heroku/heroku-buildpack-python/actions/runs/11280580537

Python 3.13 readiness status of the top 360 packages on PyPI:
https://pyreadiness.org/3.13/

GUS-W-14846841.

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Added support for Python 3.13. ([#280](https://github.com/heroku/buildpacks-python/pull/280))
+
 ## [0.18.1] - 2024-10-01
 
 ### Changed

README.md

@@ -43,13 +43,9 @@ To install a different version, add a `.python-version` file to your app's root
 
 ```term
 $ cat .python-version
-3.12
+3.13
 ```
 
-In the future this buildpack will also support specifying the Python version using:
-
-- `tool.poetry.dependencies.python` in `pyproject.toml`: [#260](https://github.com/heroku/buildpacks-python/issues/260)
-
 ## Contributing
 
 Issues and pull requests are welcome. See our [contributing guidelines](./CONTRIBUTING.md) if you would like to help.

src/layers/python.rs

@@ -176,7 +176,7 @@ fn generate_layer_env(layer_path: &Path, python_version: &PythonVersion) -> Laye
             )),
         )
         .chainable_insert(Scope::Build, ModificationBehavior::Delimiter, "CPATH", ":")
-        // Ensure Python uses a Unicode locate, to prevent the issues described in:
+        // Ensure Python uses a Unicode locale, to prevent the issues described in:
         // https://github.com/docker-library/python/pull/570
         .chainable_insert(
             Scope::All,

src/python_version.rs

@@ -20,6 +20,7 @@ pub(crate) const LATEST_PYTHON_3_9: PythonVersion = PythonVersion::new(3, 9, 20)
 pub(crate) const LATEST_PYTHON_3_10: PythonVersion = PythonVersion::new(3, 10, 15);
 pub(crate) const LATEST_PYTHON_3_11: PythonVersion = PythonVersion::new(3, 11, 10);
 pub(crate) const LATEST_PYTHON_3_12: PythonVersion = PythonVersion::new(3, 12, 7);
+pub(crate) const LATEST_PYTHON_3_13: PythonVersion = PythonVersion::new(3, 13, 0);
 
 /// The Python version that was requested for a project.
 #[derive(Clone, Debug, PartialEq)]
@@ -163,7 +164,8 @@ pub(crate) fn resolve_python_version(
         (3, 10, None) => Ok(LATEST_PYTHON_3_10),
         (3, 11, None) => Ok(LATEST_PYTHON_3_11),
         (3, 12, None) => Ok(LATEST_PYTHON_3_12),
-        (3, 13.., _) | (4.., _, _) => Err(ResolvePythonVersionError::UnknownVersion(
+        (3, 13, None) => Ok(LATEST_PYTHON_3_13),
+        (3, 14.., _) | (4.., _, _) => Err(ResolvePythonVersionError::UnknownVersion(
             requested_python_version.clone(),
         )),
         (major, minor, Some(patch)) => Ok(PythonVersion::new(major, minor, patch)),
@@ -182,7 +184,7 @@ mod tests {
     use super::*;
 
     const OLDEST_SUPPORTED_PYTHON_3_MINOR_VERSION: u16 = 8;
-    const NEWEST_SUPPORTED_PYTHON_3_MINOR_VERSION: u16 = 12;
+    const NEWEST_SUPPORTED_PYTHON_3_MINOR_VERSION: u16 = 13;
 
     #[test]
     fn python_version_url() {

tests/fixtures/python_3.13/.python-version

@@ -0,0 +1 @@
+3.13

tests/python_version_test.rs

@@ -1,6 +1,7 @@
 use crate::python_version::{
     PythonVersion, DEFAULT_PYTHON_FULL_VERSION, DEFAULT_PYTHON_VERSION, LATEST_PYTHON_3_10,
-    LATEST_PYTHON_3_11, LATEST_PYTHON_3_12, LATEST_PYTHON_3_8, LATEST_PYTHON_3_9,
+    LATEST_PYTHON_3_11, LATEST_PYTHON_3_12, LATEST_PYTHON_3_13, LATEST_PYTHON_3_8,
+    LATEST_PYTHON_3_9,
 };
 use crate::tests::{builder, default_build_config};
 use indoc::{formatdoc, indoc};
@@ -90,6 +91,12 @@ fn python_3_12() {
     builds_with_python_version("tests/fixtures/python_3.12", &LATEST_PYTHON_3_12);
 }
 
+#[test]
+#[ignore = "integration test"]
+fn python_3_13() {
+    builds_with_python_version("tests/fixtures/python_3.13", &LATEST_PYTHON_3_13);
+}
+
 fn builds_with_python_version(fixture_path: &str, python_version: &PythonVersion) {
     let PythonVersion {
         major,