tools: Remove unnecessary import statement for GLib

The make_schema.py tool is not using GLib, nor importing data that
requires the GLib introspection API.

This causes a build failure in Continuous:

  File "../tools/make_schema.py", line 3, in <module>
        from gi.repository import GLib
from gi.repository import GLib
ImportErrorImportError: : No module named gi.repository
No module named gi.repository

1 files changed, 0 insertions, 1 deletions

diff --git a/tools/make_schema.py b/tools/make_schema.py
index 5633594..2d409f7 100755
--- a/tools/make_schema.py
+++ b/tools/make_schema.py
@@ -1,6 +1,5 @@
 #!/usr/bin/python
 
-from gi.repository import GLib
 import xml.dom.minidom
 
 import os, sys