Change build container for Ubuntu/Debian

Ubuntu 18.04 doesn't work due to an outdated meson.

Author: qzed

.github/workflows/release.yml

@@ -10,7 +10,7 @@ jobs:
   build-deb:
     name: Debian
     runs-on: ubuntu-latest
-    container: ubuntu:18.04
+    container: ubuntu:20.04
 
     steps:
     - name: Checkout code