codeql: empty env section is invalid

.github/workflows/codeql-analysis.yml

@@ -27,9 +27,6 @@ jobs:
         # CodeQL supports [ 'cpp', 'csharp', 'go', 'java', 'javascript', 'python', 'ruby' ]
         # Learn more about CodeQL language support at https://git.io/codeql-language-support
 
-    env:
-      # nothing special right now
-
     steps:
     - name: Checkout repository
       uses: actions/checkout@v2