GHA: run matrix only if Ubuntu 3.8 has completed

.github/workflows/python-runners.yml

 name: Ubuntu, MacOS, Windows machines
 
 on:
-  push:
-    paths-ignore:
-      - '.circleci/**'
-  pull_request:
+  workflow_run:
+    workflows:
+      - "Ubuntu 3.8"
+    types:
+      - completed
   # Allow to run this workflow manually from the Actions tab
   workflow_dispatch:
 
@@ -12,7 +13,7 @@ jobs:
   build:
 
     runs-on: ${{ matrix.os }}
-    if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name
+    if: (github.event_name == 'workflow_dispatch') || ((github.event_name == 'workflow_run') && (github.event.workflow_run.conclusion == 'success'))
     strategy:
       fail-fast: false
       matrix:

.github/workflows/ubuntu-default.yml

+name: Ubuntu 3.8
+
+on:
+  push:
+    paths-ignore:
+      - '.circleci/**'
+  pull_request:
+  # Allow to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+jobs:
+  build:
+
+    runs-on: ${{ matrix.os }}
+    if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest]
+        python-version: ["3.8"]
+        exclude:
+          # excludes 2.7 on windows as chocolatey does not support it anymore
+          - os: windows-latest
+            python-version: 2.7
+
+    steps:
+    - uses: actions/checkout@v3
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v4
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Cache eggs
+      uses: actions/cache@v3
+      with:
+        path: eggs
+        key: ${{ matrix.os }}-${{ matrix.python-version }}-eggs
+    - name: Run tests
+      env:
+        TMPDIR: ${{ env.HOME }}/AppData/Local/Temp
+        TMP: ${{ env.HOME }}/AppData/Local/Temp
+        TEMP: ${{ env.HOME }}/AppData/Local/Temp
+        BUILD_TYPE: bare_machines
+      run: |
+        echo $TMPDIR
+        ./ci_build.sh