CI: Update Pi OS Stretch sources.list apt repository URL (#2477)

As raspberry pi has moved the repository URL to a different location.
It is no longer updated, but will be fine to install whatever is the
latest version there of the apt packages required.

Also increased the timeout because somehow the Stretch runner
is taking longer to complete.

.github/workflows/test.yml

@@ -100,7 +100,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        docker-tag: ['buster-2021-05-28', 'buster-legacy-2022-04-07']
+        docker-tag: ['stretch-2018-03-13', 'buster-2021-05-28', 'buster-legacy-2022-04-07']
       fail-fast: false
     services:
       rpios:
@@ -126,6 +126,16 @@ jobs:
             git checkout --progress FETCH_HEAD
             echo "cd ~/mu" > ~/.bashrc_new && cat ~/.bashrc >> ~/.bashrc_new
             rm ~/.bashrc && mv ~/.bashrc_new ~/.bashrc
+      # As Pi OS stretch is no longer supported the repository URL was moved and is no longer updated
+      - name: Update Stretch sources.list
+        if: ${{ matrix.docker-tag == 'stretch-2018-03-13' }}
+        uses: appleboy/ssh-action@master
+        with:
+          host: rpios
+          username: pi
+          password: raspberry
+          port:  ${{ job.services.rpios.ports[5022] }}
+          script: echo "deb http://legacy.raspbian.org/raspbian/ stretch main contrib non-free rpi" | sudo tee /etc/apt/sources.list
       - name: Install Mu extra apt dependencies
         uses: appleboy/ssh-action@master
         with:
@@ -171,5 +181,6 @@ jobs:
           username: pi
           password: raspberry
           port:  ${{ job.services.rpios.ports[5022] }}
-          command_timeout: 30m
+          # The time out can be decreased to 30 min when Stretch is dropped
+          command_timeout: 45m
           script: xvfb-run python make.py check