Move check_dependencies.py to contrib/

Change-Id: I8def867b1042cbb98bb36ff4a473b4cdb92ce122
diff --git a/Makefile b/Makefile
index c36aa9a..38ff6c8 100644
--- a/Makefile
+++ b/Makefile
@@ -3,7 +3,7 @@
 .PHONY: version check
 
 deps:
-	./check_dependencies.py
+	./contrib/check_dependencies.py
 
 version:
 	./update_version.sh