CI: run on ubuntu-latest

Author: forrest79

.github/workflows/build.yml

@@ -8,7 +8,7 @@ on:
 
 jobs:
   run:
-    runs-on: 'ubuntu-20.04'
+    runs-on: 'ubuntu-latest'
 
     strategy:
       matrix:

.github/workflows/check-new-version.yml

@@ -6,7 +6,7 @@ on:
 
 jobs:
   run:
-    runs-on: 'ubuntu-20.04'
+    runs-on: 'ubuntu-latest'
 
     steps:
       - name: Checkout