add newline when bumping version in singularity file

scripts/bump-version.py

@@ -42,6 +42,6 @@ lines = open(vfile).readlines()
 for i, line in enumerate(lines):
   if line.startswith("From: registry.scicore.unibas.ch/schwede/openstructure:"):
     lines[i] = 'From: registry.scicore.unibas.ch/schwede/openstructure:'+\
-      '%s' % version_string
+      '%s\n' % version_string
     break
 open(vfile, "w").writelines(lines)