codeql: fix error "Resource not accessible by integration"

- Enable codeql writing security-events.

GitHub set the default permissions to read, apparently since earlier
this year.

Ref: https://github.com/github/codeql-action/issues/464
Ref: https://github.blog/changelog/2021-04-20-github-actions-control-permissions-for-github_token/

Fixes https://github.com/curl/curl/issues/7575
Closes https://github.com/curl/curl/pull/7576

.github/workflows/codeql-analysis.yml

@@ -13,6 +13,9 @@ on:
   schedule:
     - cron: '0 0 * * 4'
 
+permissions:
+  security-events: write
+
 jobs:
   codeql:
     runs-on: ubuntu-latest