Fix GitHub Action to run all test commands in matrix

Previously, only the first line of `test_commands` was executed due to improper handling of multiline strings. Switched to `printf` with process substitution to ensure all test commands are run sequentially.

Signed-off-by: Marvin Froeder <marvin@datasqrl.com>

Author: velo

.github/workflows/build.yml

@@ -96,7 +96,7 @@ jobs:
           echo "::group::Running: $cmd"
           docker run -i -p 8888:8888 -p 8081:8081 -p 9092:9092 --rm -v $PWD:/build datasqrl/cmd:${SQRL_VERSION} $cmd
           echo "::endgroup::"
-        done <<< "${{ matrix.test_commands }}"
+        done < <(printf '%s\n' "${{ matrix.test_commands }}")
 
     - name: Write Dockerfile
       run: |