ci: correctly print install tree of CMake install

.github/workflows/main.yml

@@ -96,7 +96,7 @@ jobs:
         set -eu
         cmake --install build/ --config Release
         echo "SDL3_DIR=$(pwd)/cmake_prefix" >> $GITHUB_ENV
-        ( cd cmake_prefix; find ) | LC_ALL=C sort -u
+        ( cd cmake_prefix; find . ) | LC_ALL=C sort -u
     - name: Configure (Autotools)
       if: matrix.platform.autotools
       run: |