bump runner, so that we get an updated version of openssl

OpenSSL 1.1.1f-1ubuntu2.22 in Ubuntu 20.04 https://github.com/actions/runner-images/blob/main/images/ubuntu/Ubuntu2004-Readme.md
OpenSSL 3.0.2-0ubuntu1.15 in Ubuntu 22.04 https://github.com/actions/runner-images/blob/main/images/ubuntu/Ubuntu2204-Readme.md

Author: umbynos

Diff for: .github/workflows/check-certificates.yml

@@ -26,7 +26,7 @@ jobs:
     if: >
       (github.event_name != 'pull_request' && github.repository == 'arduino/arduino-create-agent') ||
       (github.event_name == 'pull_request' && github.event.pull_request.head.repo.full_name == 'arduino/arduino-create-agent')
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
 
     strategy:
       fail-fast: false