feature: add update-environment input (#411)

This option allows to specify if the action shall update environment variables (default) or not.
This allows to use the setup-python action in a composite action without side effect (except downloading/installing python if version is missing).

.github/workflows/test-pypy.yml

@@ -65,3 +65,29 @@ jobs:
           EXECUTABLE=${EXECUTABLE%%-*}  # remove any -* suffixe
           ${EXECUTABLE} --version
         shell: bash
+
+  setup-pypy-noenv:
+    name: Setup PyPy ${{ matrix.pypy }} ${{ matrix.os }} (noenv)
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [macos-latest, windows-latest, ubuntu-18.04, ubuntu-latest]
+        pypy: ['pypy2.7', 'pypy3.7', 'pypy3.8', 'pypy3.9-nightly']
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+
+      - name: setup-python ${{ matrix.pypy }}
+        id: setup-python
+        uses: ./
+        with:
+          python-version: ${{ matrix.pypy }}
+          update-environment: false
+
+      - name: PyPy and Python version
+        run: ${{ steps.setup-python.outputs.python-path }} --version
+
+      - name: Run simple code
+        run: ${{ steps.setup-python.outputs.python-path }} -c 'import math; print(math.factorial(5))'