CI: Use CEF 4280 on GH Actions builds

.github/workflows/main.yml

@@ -16,7 +16,7 @@ on:
 
 env:
   MACOS_CEF_BUILD_VERSION: '4183'
-  LINUX_CEF_BUILD_VERSION: '3770'
+  LINUX_CEF_BUILD_VERSION: '4280'
   CEF_VERSION: '75.1.16+g16a67c4+chromium-75.0.3770.100'
 
 jobs: