chore: update ci runner

Author: ttimochan

.github/workflows/build.yml

@@ -11,7 +11,7 @@ jobs:
         build: [linux]
         include:
           - build: linux
-            os: ubuntu-20.04
+            os: ubuntu-latest
             rust: stable
             target: x86_64-unknown-linux-musl
             archive-name: processforlinux-linux.tar.gz