Deal with Ubuntu 20.04 Actions runner image deprecation (#2143)

* 20.04 to "latest"

* Update .github/workflows/json-check.yml

Co-authored-by: george <[email protected]>

* Update .github/workflows/python-ci.yml

Co-authored-by: george <[email protected]>

---------

Co-authored-by: george <[email protected]>

Author: minhkhul

.github/workflows/json-check.yml

@@ -11,7 +11,7 @@ on:
 
 jobs:
   build:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     if: github.event.pull_request.draft == false
     steps:
     - uses: actions/checkout@v2

.github/workflows/python-ci.yml

@@ -12,7 +12,7 @@ on:
 
 jobs:
   build:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     if: github.event.pull_request.draft == false
     strategy:
       matrix: