CI: Fix not available on Ubuntu 20.04 LTS

Author: tsukumijima

.github/workflows/Dockerfile

@@ -1,6 +1,8 @@
 ARG IMAGE
 FROM ${IMAGE}
 ENV DEBIAN_FRONTEND=noninteractive
+RUN apt-get update && apt-get install -y software-properties-common && \
+    add-apt-repository -y ppa:ubuntu-support-team/meson
 RUN apt-get update && apt-get install -y --no-install-recommends \
         build-essential \
         debhelper \

.github/workflows/build_and_release.yml

@@ -35,8 +35,7 @@ jobs:
         with:
           context: .github/workflows/
           tags: ${{ matrix.image }}:build
-          # meson >= 0.54.0 is not available in Ubuntu 20.04
-          build-args: IMAGE=${{ matrix.image }}:22.04
+          build-args: IMAGE=${{ matrix.image }}:20.04
           cache-from: type=gha,scope=${{ matrix.image }}
           cache-to: type=gha,scope=${{ matrix.image }},mode=max
           load: true