Install packages in a virtualenv

CHANGELOG.md

@@ -11,6 +11,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - A [problem matcher](https://github.com/actions/toolkit/blob/main/docs/problem-matchers.md) so you can see issues without trawling through logs
 
+### Fixed
+
+- Packages are installed into a virtualenv due to the fact that system-wide
+  installs fail by default when run on newer versions of Python.
+
 ## [1.1.0] - 2022-11-04
 
 - All inputs changed to use kebab-case: `isort-version`, `sort-paths`, and

action.yml

@@ -72,6 +72,11 @@ runs:
   steps:
     - run: $GITHUB_ACTION_PATH/bin/ensure_python
       shell: bash
+    - run: python -m venv "${HOME}/isort-venv"
+      shell: bash
+    - run: >
+        source "${HOME}/isort-venv/bin/activate"
+        echo "PATH=${PATH}" >> "${GITHUB_ENV}"
     - run: >
         $GITHUB_ACTION_PATH/bin/install_packages
         ${{ inputs.isort-version || inputs.isortVersion }}

bin/install_packages

@@ -4,6 +4,7 @@ isort_version=$1
 requirements_files=$2
 
 echo "::group::Install isort"
+
 if [ -z "$isort_version" ] || [ "$isort_version" == "latest" ]; then
     echo "Installing latest version of isort"
     python3 -m pip install "isort[requirements_deprecated_finder,pipfile_deprecated_finder]"