fix(lambda-python-alpha): pipenv lock -r is no longer supported (#28317)

As part of the pipenv release 2022.8.13 the deprecated way of generating requirements ("pipenv install -r" or "pipenv lock -r") has been removed in favor of the "pipenv requirements" command.

See  #28015 for the motivation behind this change.

* [Reference to pipenv CHANGELOG](https://github.com/pypa/pipenv/blob/main/CHANGELOG.md#2022813-2022-08-13)
* [Refernce to relevant pipenv pull request](pypa/pipenv#5200)

Closes #28015 .

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/aws-lambda-python-alpha/lib/packaging.ts

@@ -58,7 +58,7 @@ export class Packaging {
       dependenciesFile: DependenciesFile.PIPENV,
       // By default, pipenv creates a virtualenv in `/.local`, so we force it to create one in the package directory.
       // At the end, we remove the virtualenv to avoid creating a duplicate copy in the Lambda package.
-      exportCommand: `PIPENV_VENV_IN_PROJECT=1 pipenv lock -r > ${DependenciesFile.PIP} && rm -rf .venv`,
+      exportCommand: `PIPENV_VENV_IN_PROJECT=1 pipenv requirements > ${DependenciesFile.PIP} && rm -rf .venv`,
     });
   }
 

packages/@aws-cdk/aws-lambda-python-alpha/test/bundling.test.ts

@@ -193,7 +193,7 @@ test('Bundling a function with pipenv dependencies', () => {
     bundling: expect.objectContaining({
       command: [
         'bash', '-c',
-        'rsync -rLv /asset-input/ /asset-output/python && cd /asset-output/python && PIPENV_VENV_IN_PROJECT=1 pipenv lock -r > requirements.txt && rm -rf .venv && python -m pip install -r requirements.txt -t /asset-output/python',
+        'rsync -rLv /asset-input/ /asset-output/python && cd /asset-output/python && PIPENV_VENV_IN_PROJECT=1 pipenv requirements > requirements.txt && rm -rf .venv && python -m pip install -r requirements.txt -t /asset-output/python',
       ],
     }),
   }));
@@ -221,7 +221,7 @@ test('Bundling a function with pipenv dependencies with assetExcludes', () => {
     bundling: expect.objectContaining({
       command: [
         'bash', '-c',
-        "rsync -rLv --exclude='.ignorefile' /asset-input/ /asset-output/python && cd /asset-output/python && PIPENV_VENV_IN_PROJECT=1 pipenv lock -r > requirements.txt && rm -rf .venv && python -m pip install -r requirements.txt -t /asset-output/python",
+        "rsync -rLv --exclude='.ignorefile' /asset-input/ /asset-output/python && cd /asset-output/python && PIPENV_VENV_IN_PROJECT=1 pipenv requirements > requirements.txt && rm -rf .venv && python -m pip install -r requirements.txt -t /asset-output/python",
       ],
     }),
   }));