[ci] Remove duplicate concurrency configuration

Should've seen that one coming.

Fixes #6 fr this time?

Author: CodingCellist

.github/workflows/pelican.yml

@@ -50,11 +50,6 @@ env:
   OUTPUT_PATH: "output/"
   WORKING_DIR: "./src"
 
-# Allow one concurrent deployment
-concurrency:
-  group: "pages"
-  cancel-in-progress: true
-
 # Sets permissions of the GITHUB_TOKEN to allow deployment to GitHub Pages
 permissions:
   contents: read