fix: upgrade ubuntu

Author: seveibar

.github/workflows/release.yml

@@ -7,7 +7,7 @@ jobs:
   release:
     if: "!contains(github.event.head_commit.message, 'skip ci')"
     name: Release
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     steps:
       - name: Checkout
         uses: actions/checkout@v1