syntax error in push.yml.

Author: dvanhorn

.github/workflows/push.yml

@@ -25,7 +25,7 @@ jobs:
       run: |
         export LINK_DIR=/usr/lib/x86_64-linux-gnu
         raco pkg install --auto ziggy/
-	raco pkg install langs/
+        raco pkg install langs/
         raco make www/main.scrbl
         raco test langs
         make -C www main