Fix dist-check for LilyPond 2.23.5

There are now so many .ly files that Python complains if passing
all of them as a list to os.popen. Instead use a find invocation
to get the list dynamically.

test-lily/dist-check.py

@@ -82,13 +82,7 @@ def check_files (tarball, repo):
     files = [f.strip () for f in files]
 
     ## .ly files
-    ly_files  = [f for f in files
-                 if re.search (r'\.ly$', f)]
-
-
-    ly_file_str = ' '.join (ly_files)
-
-    no_version = popen (r"cd %(dir)s && grep '\\version' -L %(ly_file_str)s" % locals ()).readlines ()
+    no_version = popen (r"cd %(dir)s && grep '\\version' -L $(find . -name '*.ly')" % locals ()).readlines ()
     if no_version:
         printf ('Files without \\version: ')
         printf ('\n'.join (no_version))