Use /proc/meminfo for Memory module

include/modules/memory.hpp

@@ -1,7 +1,7 @@
 #pragma once
 
 #include <fmt/format.h>
-#include <sys/sysinfo.h>
+#include <stdio.h>
 #include "util/chrono.hpp"
 #include "ALabel.hpp"
 
@@ -12,6 +12,9 @@ class Memory : public ALabel {
     Memory(const Json::Value&);
     auto update() -> void;
   private:
+    unsigned long memtotal_;
+    unsigned long memfree_;
+    void parseMeminfo();
     waybar::util::SleeperThread thread_;
 };