Update heroku/buildpacks-python to v0.18.0

## heroku/python

### Added

- The Python version can now be configured using a `.python-version` file. Both the `3.X` and `3.X.Y` version forms are supported. ([#272](heroku/buildpacks-python#272))

### Changed

- pip is now only available during the build, and is longer included in the final app image. ([#264](heroku/buildpacks-python#264))
- Improved the error messages shown when an end-of-life or unknown Python version is requested. ([#272](heroku/buildpacks-python#272))

builder-20/builder.toml

@@ -43,7 +43,7 @@ version = "0.20.1"
 
 [[buildpacks]]
   id = "heroku/python"
-  uri = "docker://docker.io/heroku/buildpack-python@sha256:c2b071f00e456f5914e273e12cbc4bb35baf9d3c08b06d86bc7e585c0581baf6"
+  uri = "docker://docker.io/heroku/buildpack-python@sha256:e2ec6cad5e8bf61ea0a0babc02bd01bdc7471650a04555d9d6ab785190a279ec"
 
 [[buildpacks]]
   id = "heroku/ruby"
@@ -56,7 +56,7 @@ version = "0.20.1"
 [[order]]
   [[order.group]]
     id = "heroku/python"
-    version = "0.17.1"
+    version = "0.18.0"
   [[order.group]]
     id = "heroku/procfile"
     version = "3.1.2"

builder-22/builder.toml

@@ -43,7 +43,7 @@ version = "0.20.1"
 
 [[buildpacks]]
   id = "heroku/python"
-  uri = "docker://docker.io/heroku/buildpack-python@sha256:c2b071f00e456f5914e273e12cbc4bb35baf9d3c08b06d86bc7e585c0581baf6"
+  uri = "docker://docker.io/heroku/buildpack-python@sha256:e2ec6cad5e8bf61ea0a0babc02bd01bdc7471650a04555d9d6ab785190a279ec"
 
 [[buildpacks]]
   id = "heroku/ruby"
@@ -56,7 +56,7 @@ version = "0.20.1"
 [[order]]
   [[order.group]]
     id = "heroku/python"
-    version = "0.17.1"
+    version = "0.18.0"
   [[order.group]]
     id = "heroku/procfile"
     version = "3.1.2"

builder-24/builder.toml

@@ -43,7 +43,7 @@ mirrors = ["public.ecr.aws/heroku/heroku:24"]
 
 [[buildpacks]]
   id = "heroku/python"
-  uri = "docker://docker.io/heroku/buildpack-python@sha256:c2b071f00e456f5914e273e12cbc4bb35baf9d3c08b06d86bc7e585c0581baf6"
+  uri = "docker://docker.io/heroku/buildpack-python@sha256:e2ec6cad5e8bf61ea0a0babc02bd01bdc7471650a04555d9d6ab785190a279ec"
 
 [[buildpacks]]
   id = "heroku/ruby"
@@ -56,7 +56,7 @@ mirrors = ["public.ecr.aws/heroku/heroku:24"]
 [[order]]
   [[order.group]]
     id = "heroku/python"
-    version = "0.17.1"
+    version = "0.18.0"
   [[order.group]]
     id = "heroku/procfile"
     version = "3.1.2"