ci: fix git in docker (#1623)

.github/workflows/build.yml

@@ -160,6 +160,8 @@ jobs:
         if: matrix.should_run == true
         shell: docker exec -t builder sh -eu {0}
         run: |
+          chmod -R 777 dist-newstyle ~/.cabal && git config --global --add safe.directory '*'
+          cabal clean
           cabal update
           cabal build --jobs=$(nproc) --enable-tests -fserver_postgres
           mkdir -p /out