Add unistd.h include for sleep()

It appears this was previously included implicitly, but with my next commit this is no longer the true.

Add unistd.h include for sleep()
It appears this was previously included implicitly, but with my next commit this is no longer the true.
1e2820c1 · Alex Richardson · 9b2a05aa · 1e2820c1
Commit 1e2820c1 authored May 15, 2022 by Alex Richardson
--- a/src/service/plugins/sqlite/ResourceScoreMaintainer.cpp
+++ b/src/service/plugins/sqlite/ResourceScoreMaintainer.cpp
@@ -12,7 +12,7 @@
 #include <QMutex>

 // System
-#include <time.h>
+#include <unistd.h>

 // Utils
 #include <utils/d_ptr_implementation.h>