update syntax

Author: parthea

.github/workflows/tests.yaml

@@ -20,7 +20,6 @@ env:
   # Use Python 3.10 for docs to match the version for the sphinx plugin
   # https://github.com/googleapis/synthtool/pull/1891
   DOCS_PYTHON: "3.10"
-  OLDEST_PYTHON: "3.7"
   NEWEST_STABLE_PYTHON: "3.13"
   PRERELEASE_PYTHON: "3.14"
 
@@ -35,6 +34,16 @@ jobs:
       run: |
         all_python=$(echo ${{ vars.ALL_PYTHON }} | jq -Rrc 'split(",")')
         echo "all_python=$all_python" >> "$GITHUB_OUTPUT"
+  newest_oldest_python_setup:
+    runs-on: ubuntu-latest
+    outputs:
+      all_python: ${{ steps.newest_oldest_python.outputs.all_python }}
+    steps:
+    - name: Set up newest and oldest python
+      id: newest_oldest_python_setup
+      run: |
+        newest_oldest_python=$(echo ${{ vars.ALL_PYTHON }} | jq -Rrc 'split(",")[0, -1]' ) 
+        echo "newest_oldest_python=$newest_oldest_python" >> "$GITHUB_OUTPUT"
   docs:
     runs-on: ubuntu-latest
     steps:
@@ -71,11 +80,12 @@ jobs:
       - name: Check type annotations.
         run: nox -s mypy-${{ matrix.python }}
   showcase:
+    needs: newest_oldest_python_setup
     strategy:
       # Run showcase tests on the lowest and highest supported runtimes
       matrix:
         # TODO(https://github.com/googleapis/gapic-generator-python/issues/2121) Remove `showcase_w_rest_async` target when async rest is GA.
-        python: [${OLDEST_PYTHON}, ${NEWEST_STABLE_PYTHON}]
+        python: ${{ fromJSON(needs.newest_oldest_python_setup.outputs.newest_oldest_python) }}
         target: [showcase, showcase_w_rest_async]
         logging_scope: ["", "google"]