scripts: fix file writing in convert-spdx-licenses

The convert-spdx-licenses.py script needs the same file closing
fix as was made to convert-variable-renames to ensure modified
file contents get flushed out.

(From OE-Core rev: 46135c87345c7189053dafbed92c754f9f328c32)

Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/contrib/convert-spdx-licenses.py

@@ -114,6 +114,7 @@ def processfile(fn):
                     if orig != line:
                         modified = True
                     new_file.write(line)
+        new_file.close()
         if modified:
             shutil.copymode(fn, abs_path)
             os.remove(fn)