Merge pull request espnet#4376 from kamo-naoyuki/libsndfile

Remove the restriction for libsndfile version

tools/Makefile

@@ -67,7 +67,7 @@ sox.done: activate_python.sh
 	. ./activate_python.sh && { command -v sox || conda install -y sox -c conda-forge; }
 	touch sox.done
 sndfile.done: activate_python.sh
-	. ./activate_python.sh && { python3 -c "from ctypes.util import find_library as F; assert F('sndfile') is not None" || conda install -y libsndfile=1.0.28 -c conda-forge; }
+	. ./activate_python.sh && { python3 -c "from ctypes.util import find_library as F; assert F('sndfile') is not None" || conda install -y libsndfile -c conda-forge; }
 	touch sndfile.done
 ifneq ($(strip $(USE_CONDA)),)
 conda_packages.done: bc.done cmake.done flac.done ffmpeg.done sox.done sndfile.done