Use latest Py 3.8 & different method to (not) render QT during tests/…

…build.

.github/workflows/deploy-test.yml

@@ -10,9 +10,9 @@ jobs:
     runs-on: ubuntu-latest
     if: "!contains(github.event.head_commit.message, 'ci-skip') && !contains(github.event.head_commit.message, 'skip-ci')"
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Login to GitHub Container Registry
-        uses: docker/login-action@v1
+        uses: docker/login-action@v3
         with:
           registry: ghcr.io
           username: ${{ github.actor }}
@@ -47,4 +47,4 @@ jobs:
       - name: Build Mu AppImage
         run: |
           cd mu
-          xvfb-run make linux
+          QT_QPA_PLATFORM=offscreen make linux

Dockerfile

@@ -10,9 +10,9 @@ ENV DEBIAN_FRONTEND=noninteractive
 RUN apt-get update -qq && \
     apt-get install -y --no-install-recommends ca-certificates wget && \
     apt-get autoremove -y && apt-get clean -y && rm -rf /var/lib/apt/lists/* && \
-    wget https://github.com/indygreg/python-build-standalone/releases/download/20220502/cpython-3.8.13+20220502-x86_64-unknown-linux-gnu-install_only.tar.gz && \
-    tar -xf cpython-3.8.13+20220502-x86_64-unknown-linux-gnu-install_only.tar.gz -C / && \
-    rm cpython-3.8.13+20220502-x86_64-unknown-linux-gnu-install_only.tar.gz && \
+    wget https://github.com/indygreg/python-build-standalone/releases/download/20241002/cpython-3.8.20+20241002-x86_64-unknown-linux-gnu-install_only.tar.gz && \
+    tar -xf cpython-3.8.20+20241002-x86_64-unknown-linux-gnu-install_only.tar.gz -C / && \
+    rm cpython-3.8.20+20241002-x86_64-unknown-linux-gnu-install_only.tar.gz && \
     ln -s /python/bin/python3.8 /bin/python && \
     ln -s /python/bin/python3.8 /bin/python3
 ENV PATH /python/bin:$PATH