docs: use apt-get instead of apt-fast for action

Author: laytan

.github/workflows/docs.yml

@@ -28,7 +28,7 @@ jobs:
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
       - name: Get commonmark
-        run: sudo apt-fast install libcmark-dev
+        run: sudo apt-get install libcmark-dev
       - name: Get and build Odin docs generator
         run: |
           cd /home/runner