[FIX] Use find's maxdepth to ensure correct library

To avoid finding multiple directories that have 'python' in the name
under /usr/local/lib/ on the GitHub Actions runners, use the maxdepth
option for find to limit the search to directories of the pattern
'/usr/local/lib/python3.*'.

.github/workflows/build.yml

@@ -282,7 +282,7 @@ jobs:
     - name: Verify Python bindings
       run: |
         export LD_LIBRARY_PATH="/usr/local/lib:${LD_LIBRARY_PATH}"
-        export PYTHON_VERSION_MINOR=$(_tmp=$(find /usr/local/lib/ -type d -iname "python*") && echo ${_tmp: -3}; unset _tmp)
+        export PYTHON_VERSION_MINOR=$(_tmp=$(find /usr/local/lib/ -maxdepth 1 -type d -iname "python3.*") && echo ${_tmp: -3}; unset _tmp)
         export PYTHONPATH="/usr/local/lib/python${PYTHON_VERSION_MINOR}/site-packages:${PYTHONPATH}"
         python3 -m pip list
         python3 -m pip show xrootd